What about those skirts?

[M. Demetrius]

To my eye, it just looks like a tunic folded down (with the top part on the inside) held up by a belt. It could be just a tube of cloth, I suppose, or perhaps even something like a sagum or other blanket with its edges out of sight. The large fringe makes me think it's a heavy cloth, not a thin garment cloth.

When that photo is fully enlarged, the line that looks like a seam in the small view doesn't look so convincing any more. There are no wrinkles at the top of the folded-down boot/shoe, which evidently is made from soft leather, and has a securing strap across the instep. Not entirely like an officer's military boot, but appears to have a closed toe more or less like a calceus of some kind or other. Looking at things more closely, while it's clear the boots come up and fold back down, the appearance doesn't demand any kind of trousers at all. It's not generally possible to make them so tight they would have no telltale wrinkling at the boot top, and still be able to get them on.

I think I'd vote for no trousers, unusual boots, and a kilt-like wraparound with a narrow sash somehow secured out of the visible area. It is, however, a drawing of a sculpture, so it's not for sure what the original sculpture really looks like, or if the original genuinely followed the real person. It would be helpful to see a PHOTO of the sculpture, though. Hard to know what the artist added for whatever effect, or if he copied erosion or damage lines on the sculpture and they look like seams.

So there's another opinion.