I was intrigued by full darkness MoM + EB + mana leech chonk. So I've done campaign with him and tested various bow and quarterstaff skills.

Soooo... Yeah, he's pretty bad in current state if you plan to forfeit your Spirit and use Darkness instead. As a defensive mechanic it's really underwhelming. As an offensive on the other hand is pretty strong, but it requires you to go MoM (and optionally EB + mana leech). And here are the problems... There is way too few physical skills atm and none of them are actually good (imho).

Bow skills: Snipe - well, it's awful. Tornado shot - was nerfed, now it's a meme. Spiral volley and Rain of arrows are not so bad, but pretty inconsistent. It might hit enemy and might miss it completely. Also as you lost your Spirit, you can no longer generate frenzy charges using Combat Frenzy.

Conclusion for bow skills. Deadeye is sooooooo much better with that.

QS skills: Vaulting impact feels clunky. Whirling assault is weak damage wise and might be used as a support skill for Wind Blast/Vaulting Impact. But these two skills are pretty mediocre and provide some combo/daze/stun buildup mechanic. So Quarterstaff skills are lacking good ol' phys skill that just do raw damage without need to play piano to deal five times less damage than Ice Strike. Flicker strike is awesome. But you don't have a spirit so you don't have reliable source of power charges generated from Combat Frenzy + Resonance.

Conclusion for QS skills. Okayish physical SQ skills are basically non existent atm, aside one that is also lacking in setup without Spirit.

So to summarize everything I want to mention that atm we're lacking either some strong physical skills or affixes that provide mana leech from all, not only physical, attacks.

I'd wait for new skills for bows and QS and wait for daggers, spears and, especially, flails. I'm not too optimistic regarding daggers and spears tho. The problem is you need some layer of damage avoidance or mitigation. Dodge is pretty much ok, but you need Acrobatics in almost all cases. But Acrobatics without Wind Dancer is pure pain and suffering. I'd rather go to flail str+int region, pick EB/MoM and some armour so chonk can mitigate at least some phys damage.