Brilliant minds think the same, do they not!
I like the idea of the one-use catalysts, stack of 16 is nicer, IMO especially for items like that. Special, too special for just a stack.
Speaking of which, do Ender pearls smelt in to Essence?
Another thing is, how many types of Essence are there?
Teleportation is always nice, perhaps on short distances (300 blocks max?) it uses low essence and beyond that it uses high?
I've got a ton of ideas, if you need any..