It may depend on what's your latest patch but from my games, I noticed a major difference between the skills i.e fire damage, and when a weapon you found actually was imbued with these effects i.e sword, damage 60-90, abilities: fire damage (3). While with the skills it gives a percentage chance (fire damage level 1 5%), when imbued as a weapon ability it had a 100% chance of taking effect, the level only affecting the effectiveness. With stun however, I'm not really sure, but I don't think they stack up, it probably just takes whichever level is higher between the skill in your skill tree and the level on the weapon. That's how it was with my patch (not sure what #). <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />