Yeah Aventurine's damage is nothing to snooze at. Mine is not built super well but he's probably still on-par with my offensively-geared Pela and Silver Wolf, at least. Probably ahead if I'm pairing him with a lot of follow-up attacks from his teammates.
Edit: Well, my Aventurine is probably in the middle. Surely he could have better relics but I am still sitting around 4.1k DEF and something like 90% CRIT DMG with the Salsotto planar set.
I didn't do guru this year but azuarc can be in my sig anyways.