So are bikinis with sleeves fashionable in the future, or is Shepard covering up one especially nasty scar? EDIT: checked the source, and apparently this FemShep has a prosthetic arm, and that's what the sleeve is hiding.
Honestly, this is pretty much what I've always imagined what my own Shepard would look like under her armour. Dying, coming back and getting shot probably a million times will do that to you.