Onslaught is the most useless skill
Yes. Yes it is. I's literally garbage.
Flurry in DOS1 was ok but not best skill, not "master tier" as it was depicted, but somewhat usefull (you could still deal more damage with other means in melee), but this, this is just another level of garbage "master tier" skill. This is trash beyond trashness. Even if every strike would deal 100% of weapon damage, it still would be questionable, because it is actually not auto-attacks like in DOS1, but skill, and skills do not crit from enrage -> it would deal less damage than auto-attack with enrage for two-handed.
But as it is now...its beyond useless.
Seriously, I get the distinct impression that this game heavily favors archer build.
In DOS1 archers were very, very underpowered, even gimped. Archers are good in DOS2, but I don't agree with you here, two-handed-retards (like i am) are just as good at dealing damage and also have much more gapclosers than in DOS1 (where you only had 1 charge, now you have 2 charges + 2 jumps), but unlike archers, also have a ton of HP.
So I would say it's this exact skill problem. Archers are not being favored or anything. They are just fine now.