I can create a weapon that gives the character a skill, but I'd rather have the weapon just randomly use the skill instead of the player having to select it.
E.x. :
A sword of fire
randomly on hit (during battle) the sword would use skill x
Skill x = fire damage spell of Z damage.
Much like a 'weapon proc' of modern day mmorpgs.
Having the 'random on hit' be a changeable modifier would be extra awesome.
I think having a weapon that will randomly use a skill or 'cast a spell' in this case, would add much flavor to choosing the right weapon for the job ;)
Try using "Ryex's Weapons Unleash Skills" script. Here, it's located in the script database.
http://rmrk.net/index.php/topic,35252.msg425034.html#msg425034
In the script, it lets you tag the ID of a weapon to the ID of a skill and it enables you do modify the unleash chance.