clan tartans are a relatively late concept, 17th or 18th century I believe. Before that time it simply was not practical and affordable to differentiate that finely. There was certainly regional variations, but they would be just that, regional. In the 18th century, when weaving and dyeing became more of a production business clan tartans could be designed and produced economically. Earlier tartans were dyed with natural vegetable dyes of limited colorfastness, so bright colors were uncommon. Mustards, Saffrons, some dull greens and for the wealthy, purple, were more common. Mostly the design was fairly basic, generally the universal Celtic/Gaelic check.
This kilt style is also a late design. The great kilt, dating back quite a ways, was several yards long. It was pleated by hand and the pleats were positioned behind the body to gather them out of the way until you need the extra fabric either as a blanket, cloak, purse, etc. But the Great Kilt was not common until the end of the Medieval period, well past the time of Robert the Bruce and William Wallace. It was common by the time of Rob Roy MacGregor and the Jacobite Rebellions.
This kilt style is modern and formal, appropriate for any occasion where a tuxedo might be worn so long as it is worn with other formal attire. Scottish formal attire is the only formal attire I can think of wherein large and small knives are considered polite and appropriate. A 21 inch long dirk is a truly formidable personal weapon so long as there aren't any guns around. Even a Sgain Dubh is better than nothing, especially if it's a real one and you keep it nice and sharp.