Some of the Homunculi have an "Ultimate Weapon" moniker: Greed the Ultimate Shield, Lust the Ultimate Spear and Wrath the Ultimate Eye. What would the others ones have?
-Gluttony has a mock-Gate in his stomache, so maybe he'd be "The Ultimate Door".
-Envy can take any form, so how about "The Ultimate Mirror"?
-Pride controls a big amorphous mass of darkness, so "Ultimate Shadow" comes to mind.
-Sloth's job is to dig tunnels all around the county. He is... "The Ultimate Shovel".
Any other ideas?