I made some trys with 3 weapons (Branch, Quaterstaff and Machette, which have different cooldown) on characters without any weapon skill. I look damage for strength of 9, 11, 24, 26 and 27 then made some maths.
It appear that basic damage in the tooltip of the weapons is damage for a strength of 10. Then each strength point up (or down) this base will up (down) minimum damage by 0,5 (rounded down) and maximum damage by 1.
Since the formula doesn't change with cooldown of weapons, fast (low cooldown) weapons will be relatively more damage efficient with high strength and slow (high cooldown) weapons will be relatively few damage efficient with high strength.
I suppose this maths are corrects for dexterity-based item (melee or missile) and for throwing weapons but this need some more tests.
Hope my english isn't too bad, it's not my native tongue
