Cast it! is a simple and yet powerful plugin for Decal 3.
Simply wield the weapon you want to fight with, and press the 'BuffMe' button, hotkey (or type /ci/buffme in the chat box and Cast It! will do the rest. It automatically switches to your casting wand, prebuffs you to the best cast ability you can reach (uses 'ladder' buffs to maximize the skill), then buffs you, your weapon and any other weapons you have selected for it to buff.