From an in-fiction perspectives, poisons are basically the same thing as varnishes. Tiny vials that you carry around on your person for the purposes of coating a weapon to inflict greater harm that generally require you to kill something to get them. In both cases, the icon is a little vial that takes up 1 inventory box and weighs 0.3lbs.
Can we get poisons to be mechanically treated more like varnishes in the inventory system? It'd be really nice if you could stack the vials of poisons the way you can stack varnishes.