If Sword of the Ages is used to target a creature, and that creature say gets bounced in response, do I still exile the Sword and the creatures sacrificed to it's ability cost?
No. If the target of the ability becomes illegal by any means before it resolves, then all its targets are ilegal, and the ability doesn't resolve at all, it does nothing, no damage, no exiling of cards.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)