Question on using ability on back bar and weapon swapping.

flguy147ub17_ESO

For instance if i have sharpened weapon on front bar and defending on the back bar for a weapon. And lets say Sorc's Curse ability is on the back bar and i apply the curse on an enemy and then switch to the front bar then which weapon trait does curse use when it explodes? Didnt know since i applied it with back bar but it explodes on the front bar? Also does it work the same way with dots when you weapon swap? thanks.