How is experience recieved? Is it the amount of damage dealt?
For every successful strike, you receive +1.0
Except Short Blade, which is +0.75 and Axe which is +1.2
Amount of damage is not a factor.
Secondly, On-Strike drain fatigue (not made through enchanting) isn't possible, is it?
How else would you make that weapon without Enchanting??
There isn't one in the original game, if that's what you're asking, only Cast When Used.