Arcanists are currently the easiests levelers and fastest to prestige 10, and im okay with that.
But PLEASE, increase the damage of mentalist aoe. If you go ingame and speak to anyone who plays mentalist and tries to prestige they will tell you the same thing. It is cancer to level up. The low aoe radius is the first thing, but thats not a big issue.
Doing 80k aoe with 1.1k int and rank 100 wand etc is very triggering. Its extremely hard to level mentalists becaue of the extremely low aoe dmg and I remember discussing this before and you said mentalist is for bombs. But please try lvling with bombs and you will realize that it is even more aids to use than the low damage aoe.
Like a blade or any physical dps class will have 1 shot 5 mobs in the time a spirit bomb has flown to the target (having max dct does not change this) , even if it does 1 shot mobs its not fast and its just inconvenient to level that way. More over spirit bomb dosent even do that much more damage than Arcanist skills as u said, Javelin and bubble do almost the same damage maybe a little less. In fact an elementer with prestige 10 does about 500k more damage than i do with both aoe and 1 v 1 spells (yes he has all the pve prestige stuff but even without it would be about the same)
So the argument for psy = bombs and ele = aoe is not really valid.
TLDR; Psy PVE needs some love
(Just take a look at Rankings page)