So I was playing through a scenario that involved battle and siege mechanics and was wondering if I have, for example, Glorfindel with Light of Valinor attatched, does he still not exhaust to commit to a battle or siege? Or are battle and siege completely different than questing?

Battle and siege are still questing, so, Glorf with LoV will still contribute whatever stat is being used for the quest.

Glory rocks in Battles, but not in Sieges, so if you have a choice...

I was unprepared for the Siege keyword when I tried Cair Andros. Solved it by putting Light of Valinor on Elrond instead (definitely a first).

EDIT: I have rarely tried it myself, but I'm guessing that a Siege scenario is one of those few moments where Tactics decks actually get to shine. With heroes like Beregond and allies like Defender of Rammas, that is.

Siege and battle scenarios without tactics are almost impossible