If you're maxing a runeword, mo first to bypass the 350 ed cap, otherwise it doesent matter.
get ed maxed first. in terms of whether or not max damage or ewd is better however is hard to say. you prob wont need cb since trap rat and items easily max you out on it.
If leftovers, then Crushing Blow, but it's easy to go over 100% with trap rat (set, Perfect Rainbow Stones, Elfin Weapons), so calculate everything properly.