I would think if you using something repeatedly - you are bound to improve eventually.
Of cause - it should not apply to all item given skills (it might be too powerful for certain skills).
But more as a general rule.

It annoys me from time to time I keep getting bunch 'lost concentrations' on 'purge poison/decease' and can never learn how to use these fricking periapts.


Bonus idea1 (kinda opposite to what I was saying):
Use of 'exotic weapons' should be a skill (given on 25th rank perhaps).
Not automatic level*3 proficiency. This never made sense to me.

Bonus idea2:
How about giving 'wands' skill to enigma warriors and give them chance improve it. At lower learning rate then mages would.
And 'offensive use only' restriction stays.

My 0.02$

-=NNNick=-