Astarion with his default trickster subclass trades melee effectiveness for a selection of spells. If you respec him to a thief, he can hit pretty hard, and there are some build guides out there that can make him (or any thief rogue) downright fearsome. This one looks pretty good: https://mobalytics.gg/blog/baldurs-gate-3/rogue-thief-build-guide/