This suggestion has two parts. The first, and easiest to implement, is thus: I periodically de-clutter by going through my items and selling extras (like if I have 4 of the same robe). This is a needlessly time-consuming process. Could we have a tool to find and mass-sell items beyond what's needed to outfit a party? With more effort, this could be expanded into a general improvement in item search. Searching for items that remove armor, items with vampiric healing cards, etc. could be done by giving cards keywords (maybe hidden, maybe not) which could be searched for. This would save countless hours of slogging through my item collection to compare items.
It's not that hard for most cards to find some text string that is unique to that type of thing you're looking for, you just have to give it a moment of thought... for example type "each point" in the search box to find all vamp attacks (because only vamp attacks say "For each point of damage...").
About the first suggestion: we have almost literally had a 100 topics asking for a sell-excess button. I'd too still like to have it.
I know how they can implement this. Have a quantity search option while selecting a slot, then trash items above max. Do this for each slot to sell excess.
Arcane item > 12 spam click Ctrl + left click Arcane skill > 3 spam click Ctrl + left click etc Yup, I could do that every now and then. And people who farm SP will find it even more useful. Heck, this might even make me try some farming myself.