BUG FIX NEEDS TO HAPPEN TO GUNBLADE

it says in the item description that you are healed 15% of damage, so that should mean all damage to an enemy champion correct?? well i build this item on , in this build order but the problem is that when w is used it doesnt heal, and when ult is used it heals only for the first initial damage and not the consecutive damage. this build is very good imo and those issues should be fixed. RIOT FIX