Using Item inconveniences and possibilities

Hi ppl! I'm thinking about how to make a "fire breath" spell in Arcana, where you hold down right-click to shoot a continuous cone of fire. My main difficulties are in detecting which hand the currently-casting wand is in, since I need to get data from it, and figuring out how to make it so that when you stop holding right-click, the spell goes on cooldown. I use the consumable item cooldown for this, but the wand is highly versatile and can be adapted to a bunch of different right-click detection systems and whatnot. How could I do this? :3