Here's Olaus. The translation is taken from William Tegg's The Every Day Book (1825), on Plough Monday, because this translation of this section is widely quoted in readily-available sources (including online ones):
The Northern Goths and Swedes have a sport wherein they exercise their youth, consisting of a Dance with Swords in the following manner. First, with swords sheathed and erect in their hands, they dance in a triple round : then with their drawn swords held erect as before: afterwards, extending them from band to hand, they lay hold of each other’s hilts and points, and, while they are wheeling more moderately round and changing their order, throw themselves into the figure of a hexagon, which they call a rose: but, presently raising and drawing back their swords, they undo that figure, in order to form with them a four-square rose, that they may rebound over the head of each other. Lastly, they dance rapidly backwards, and, vehemently rattling the sides of their swords together, conclude their sport. Pipes, or songs (sometimes both), direct the measure, which, at first, is slow, but, increasing afterwards, becomes a very quick one towards the conclusion.A few notes on how to turn this into something a little more practical are in order before I present my full version. First, it should be noted that Olaus's illustration shows people dressed in a similar style to one another but does not appear to depict identical uniforms, as might be expected in modern sword dances. It also doesn't show any sign of there being sheaths for the swords, so it is reasonable to substitute a similar introduction that doesn't use them if necessary.
I interpret "wheeling more moderately round and changing their order" as meaning that the dancers do a series of linked figures. Those called, in the English tradition, "Single-Under" and "Single-Over" are the most obvious candidates; there are visual depictions (albeit outside of Scandinavia) of the latter, while the former is literally the simplest linked figure in the entire hilt-and-point sword dance tradition. "Changing their order" can also be applied to any method by which the dancers turn the ring inside-out to tie a star.
The "four-square rose" is a strange phrase. (It's a quadrata rosa in the original Latin.) My current preference is to interpret this as intending something like "a rose with crossed corners" such that it refers to a six-pointed star formed of the dancers' swords. This is consistent with the description that this is something they can "rebound over the head of each other." Based on the fact that the two roses are distinguished, I interpret the first one as only half-formed, a hexagon but not a star, but I'm far from certain of this point.
The retrograda saltatione ("they dance rapidly backwards") is one spot in which I do not interpret this dance according to the most direct reading. Having the dancers simply whirl backwards seems like less of a conclusion than something a little more involved; I choose to suppose that Olaus is describing the dancers doubling back on themselves in a circular hey. This is a figure found in non-sword dances of the same period, and a few Dutch illustrations make it clear certain country dance like figures were part of the sword dance tradition in northern Europe (though there's a lack of Scandinavian sources to be sure it made it to that side of the North Sea). Such a figure is also found in many modern sword dances.
The music to many modern sword dances is in triple-time, and I find that the most natural spacing for a ring of six dancers is such that this works nicely with the hey with which I prefer to end the dance: The hey ends up going "CLASH-step-step PASS-step-step," clashing swords and passing right shoulders on "CLASH" and passing left shoulders with the next person on "PASS." (Optionally, as a twist I have no reason to suppose is historical, those three dancers passing on the inside can clash their swords together in the center of the circle.) However, any music of an appropriate tempo will do; the dancers should be walking through the various figures, but doing so in time to the music. As a melody, I favor "Spanish Ladies," but I've been keeping an eye out for similarly-paced sixteenth-century folk music with an appropriate time signature since that one's about a century later than the dance.
Here, then, is my full notation for how to dance an interpretation of Olaus's sword dance, taken from a handout used to teach the dance at Pennsic XLI a year ago.
Olaus Magnus sword dance - notation[ed. note: I didn't originally include Single-Over, because I had a limited time to teach my class in and wasn't sure it would fit. It did. Single-Over works exactly like Single-Under, except that the sword held by Nos. 1 and 2 is held low instead of high; the dancers, in turn, will step through the space between this and the sword held by Nos. 2 and 3. Like Single-Under, it can then be repeated for each dancer, in the manner of an English sword dance. A briefer but less traditional idea would be to have each dancer take a turn initiating one of these two steps, alternating between Single-Under and Single-Over.]
This is a first pass at a reconstruction of the Scandinavian chorea gladiatoria described by Olaus Magnus in 1555. In style this dance most nearly resembles modern English longsword dances such as Kirkby Malzeard. The dance is performed by six dancers, each carrying a sword (for which sticks may be substituted) of identical length, ideally around three feet; there is no Captain or other special character.
Modern sword dances are usually done with the dancers in matching costumes, but visual sources suggest that this is not a period practice. In other words, dancing in your everyday garb is not only convenient but also historically correct.
Olaus Magnus gives us almost no guidance about the music other than to tell us it is performed by pipes, voices, or both. Therefore, there was likely not one specific tune associated with the dance. For this reconstruction, the music should be in 6/8 time, moderate in tempo, and ideally period. Toward the end of the dance, the tempo will speed up, so that the final part of the dance is done quite rapidly.
Olaus gives us very little guidance on the overall style of the steps in this dance, but jigging as seen in certain modern English dances is almost certainly not appropriate. Instead, the dancers will progress through the figures in a brisk walk, stepping in time with the music as they do so. Each figure should flow smoothly into the next. While only one figure (single-under) is presented here before tying the rose, it would not be inappropriate to add additional linked figures from the English and German longsword traditions.
The dancers stand double-file with their swords sheathed but held erect in their right hands, and proceed into the performance space, where they form themselves into a circle facing clockwise (swords on the inside). They then walk around the circle three times. The swords will be removed immediately after this step; since there isn’t an obvious place to put the sheaths, this step may be left out. Now, the dancers walk around the circle three times with their swords bare and held erect. As they return to their place in the circle the final time, they make a half-turn to the right (they now all face counter-clockwise). Each dancer then lowers the point of their sword onto the right shoulder of the dancer in front of them, then brings their left hand up to their own right shoulder to take hold of the tip from behind. Now holding both swords, each dancer brings the sword on their shoulder over their head while making a quarter-turn to the left, so that all dancers face inward. They then step sideways, dancing their way around the ring for one complete circle.
Both swords held by No. 2 are raised high in the air while No. 1 faces No. 3 and stands near him, the three of them forming an arch with the two raised swords. No. 1 then steps under the arch, at which point No. 2 will have to rotate in place half a turn under the swords. No. 1 remains adjacent to No. 3, still forming the arch. No. 6 then steps under the arch of swords, followed by No. 5 and then No. 4, at which point No. 1 steps out and the circle is now re-formed. This figure is repeated with No. 2 doing the moving, then No. 3, and so forth. (This figure, and its slightly more challenging cousin Single-Over, are depicted in period visual sources, common today, and meet Olaus’s description of the dancers wheeling moderately round and changing their order.)
Inversion[ed. note: here I originally offered an alternate concluding step that basically just said "dance rapidly backwards." I don't like it, so I'm leaving it out now.]
While the rose (below) may be tied without this step as it is today, Olaus describes the dancers as remaining linked, which suggests a step is necessary to turn the circle inside out. This may be accomplished most easily by having No. 1 hold their sword low to the ground, after which No. 6 steps over it, then No. 5 and so forth. Ultimately the dancers will be standing in a ring, facing out.
The dancers now form a hexagonal figure called the “Rose.” This is done by having each dancer make a half turn toward their left, bringing the sword in their right hand overhead as they do so. They are now facing inward as originally, with their right hands crossed over their left. They uncross these, crossing the swords. (At this point it is usual to finish weaving the swords together into the shape of a star, but in the Olaus dance this will not be done until the second rose below.) The dancers now let go of the swords in their left hands, then step out (backward), rapidly drawing the swords out of the figure.
The dancers link swords once more (as described in the introductory figure) and repeat the inversion of the circle (though, as the first rose has re-ordered them, No. 2 should be the first to step over the sword held between Nos. 1 and 6, followed by No. 3 and so forth). Once again the Rose is formed by turning around to the left and uncrossing the hands. This time each dancer quickly passes the point of the sword in their left hand over the hilt of the sword to their left, and the hilt of the sword in their right hand under the point of the sword whose hilt is held by the dancer to their right. This forms a star shape of interwoven swords. (Olaus refers to forming a “quadrata rosa” or “square rose,” which is a surprising description and not a trivial one to interpret. As he directs that it be held aloft and rebounded over the head of the dancers, it is highly likely that this refers to the star shape formed in most traditional sword dances, with which this can be done.)
The Rose is then held aloft by No. 1, and passed over the head of each dancer in turn. (Optionally, the dancers may be stepping around the circle clockwise while passing the Rose backwards, counterclockwise.) Once all dancers are where they started and the Rose is once again held by No. 1, it is lowered back down and the dancers once again take hold of the swords by the hilts and draw them out, untying the rose. The music now begins to accelerate for the conclusion of the dance.
Conclusion - hey
An alternative (and somewhat more challenging) step seen in Grenoside and other modern English and Basque sword dances is the hey, also used in period English country dancing and some modern morris. If we interpret the retrograda saltatione of Olaus as a doubling-back dance, it could be referring to the hey, but while it is highly likely that this is a period sword dance step, we’re on rather shaky ground including it in this dance.There you have it - a longsword dance as performed in the sixteenth century. After the dance concludes, the dancers can make a dignified exit like most modern sides, or they can do as Olaus says and disperse into the crowd, where they engage in mock fights any time two of them find one another again.
For the hey, dancers 1, 3, and 5 turn to the left (clockwise) once more, while dancers 2, 4, and 6 turn to the right (counterclockwise). All swords are held aloft in the right hand. The dancers then step around the circle. As they pass dancers going in the opposite direction, they alternate passing on the right and on the left. Every time a pair of dancers pass with their right sides toward one another (the side with the swords between them), they clash their swords together forcefully. All dancers will be doing this at the same time, and the step must be timed so that this is done with the beat of the music. Once again, the dance will be concluded by all dancers holding their swords aloft and sheathing them.
During either concluding step, the music should be accelerating in tempo, so that it is a moderate pace at first (as it is for the rest of the dance) but reaches a rapid finish.