Guys this item is just a Clue left for SE so that people could find Diabolos. yes, this is Diabolos' blood. idk wtf are Derimite doying with it because Diabolos is like 1000 time Stronger lol. Anyhow BLM is the closest thing to a SMN in relation with Nature force and Elementar powers. so he can use the Avatar blood to amplify the dark powers of DArk based MAgec. witch are everymagic but light based. is simple to understand once u think of it ^_^
But if it was made in SMN gear, the avatars would turn on us SMN who would think we killed one of their own. BLM use black magical stuff such as, manticore hairs, eye of newts, toadoil, and etc. SMN are for mana increasing and controlling avatars. Just me rambling...
Lets think about this... Avatars "abilities" are called BLOOD pacts! maybe... this item Avatar BLOOD will make the BLOOD pacts stronger... think about it.