it would probly be better to handle that sort of thing by a bunch of multable factors (ie, is more powerful agains one type of weapons but less against another, flags would be less versitile and redundant quick)
when I said I was going to make it more like the decals, I meant it would be like haveing animated decals that only get made on the sheild mesh, they would all be square(ish) and not have distorted UVs if they were too big.
the multable texture thing is a totaly unrelated subject, but while I'm in there I could probly allow this, though I think it would make more sence for each ship to have a specific sheild hit animation for it rather than each weapon, maybe give each ship sevral animations that would be used for diferent types of weapons (bombs, disrupters, mass drivers, ect)