Do you think voli needs some kind of tweaks

Yes.

He's old and outdated and it shows. He has the sort of kit that would be unbearably hard to counter if the numbers were too high while at the same time severely lacking impact on the game while the numbers are too low.

He needs a gameplay rework, honestly. He's already got a few good things built right into his kit going for him (Regeneration, single target CC based initiation, single target execution, AOE effects - All key elements of a fighter type tank who wants to be in the thick of a fight). If he can have his abilities reworked so that he's much more dynamic in play style, that would be great for him both balance wise and strength/utility wise.