It is known. Nothing under the robes.

On the Gith armor and the rest it should go either way -- either give men and women pants or take them from both. I think the aesthetic the artists were going for was high fantasy Spartan. So if Greek armor is the basis both would have greaves but otherwise bare legs.

And I'd like that representation throughout the game -- if you are going to give Wyll's patron a neckline that plunges all the way to the top of the pubis, do the same for Cazador or some other figure.