There are such staves, as well as other weapons with magic oriented attributes, it's just the RNG at work for you giving you poison daggers instead.

Initiative is awesome on everyone anyway.

Thing is there are a lot of weapons with initiative bonuses floating around - including normal ones you can start the game with or get from research+shops - and next to none with caster-specific bonuses like spell mastery (I've yet to see one actually, I don't doubt Sanati's word that they exist, but they must be rare). Sure the RNG might let you find a staff with actual caster stats, but if 9/10 games your caster winds up using a +4 initiative dagger, that seems a bit off.

Then there's the related problem that even if you had a +spell mastery or +intelligence staff, you'd probably benefit more from a +initiative dagger anyway. The whole reducing enemy resist thing seems underwhelming, you really need to be getting a damage increase to spells of some kind. If I upgrade a champion focusing on purely caster upgrades, he/she quickly gets to the point where spells never get resisted, but they hit so weakly that the caster is relegated to buffing/debuffing while my melees do all the damage. The uncommon evoker trait seems to be the only way to actually increase damage, all the actual stats related to casting don't seem to make much difference.

If you pick the "impulsive" trait(+10Initiative in the first turn) for your spell caster you can cast 2 spells or a fireball(or any spell that need one turn charging) in the first round, this is really good but OP i think.

That wouldn't be the case if a unit would have at least one retaliation par turn.

well the point is stilll that initiative from items and traits NEED to give 2x spell casts otherwiese thre would be no point into stacking it

 so its a blind road here, either we accept the system with this possibility or the whole initiative bonuses are mute

im not sure really, for example archers dont look so strong, with much initiative you can shooot 2 arrows at start but thats not really op, they dont deal that huge dmg

while shooting a fireball on the enemy chunk seems quite op, or even 2 strong single target spells on some enemy "boss"

I had this idea of maybe adding diminishing return effect to initiative so that in the first rounds of combat it works at full power but as the combat keeps going, it becomes less and less effective and towards the end of a long fight each unit has basically 0 initiative.