"One of the main reasons that people don't generally use quarterstaves at endgame is the amount of enchantments you have to give up in comparison to dual wielding sceptres, or something of the kind. This quarterstaff is even worse on that front than usual. It can have a maximum of four effects, and one of those is a presumably expensive upgrade."
This is very true. devs had started down the path of adressing staves and were, as far as i am concerned, at least, on a right path. The Dino bone staff effects were exceptionally (pun intended) well done and a great start.
In general though... Two handed Weapons of any kind - but especially for casters - need to have the equivalent of TWO one handed items (because no one and I mean NO ONE cares about damage per swing). That means FOUR augments and double the affixes. There is not a big advantage to using a staff vs two items.
So a couple of potential suggestions:
1. Staff enhancement tree. "Path of the Magi" that further enhances staff use. At least 2 Augment Effects at Capstone. Things like USP, a multiselector that enhances one type of spell power & spell lore. Perhaps a capstone "retributive strike" where you can expend something very expensive like 250 spell points and a fearsome blast of your chosen damage type affects an area.
2. Staff Destiny Path: "Runeking" where phantom runes are added to a staff you wield in ADDITION TO enhancement tree that can, for example, in tiers 3/4/5 let you pick one spell (open to suggestion) that is NOT a "mass" spell and turn it into a mass spell, such as a buff (stoneskin, shield), or a debuff (power word blind, ray of enfeeblement) instead have an AOE or party effect. or, that adds a caster level per core.
Anyway, that is just a couple of ideas, but the gist is to perhaps make staves more competitive with dual wield. Thanks!