Meanwhile: I can't understand how to improve IED and Damage Boss, other than via HyperStats
Yes, you can get IED on Secondary, Weapon, and Emblem? I believe, same with boss damage, I might be missing a couple of equips. There is also the Leafre Codex set which gives IED, Luminous Link skill, Blaster and BT Legion...
Keep in mind as well that IED is multiplicative. It functions on diminishing returns. Ex: your stat window shows that you have 70% IED. You equip something new that gives you 10% IED that you didn't have before. Your stat window now shows you have 73% instead of 80%. This is because 3 is 10% of the value remaining between 70 and 100%. I might not be absolutely correct about it, but it's more or less a simplification of things.