<Snipped quote by Skyrte>
Granted, most of what I am spouting is secondary canon, considering that it's in the games.
In Dawn of War II: Retribution, Adrastia can get an Eldar Harlequins blade which states in the description that it was gifted to the Imperium. It's description is something along the lines of:
"It's rare for the Eldar to allow humanity to handle their technology, but for unknown reasons, sometimes the doors of the Black Library open to allow some relics to be removed for Inquisition study."
Essentially, they give humans technology under the permission that they use them on Slaanesh and its worshippers.
Also, according to a friend, Eldar Life Debts are an Oldhammer thing, this was from the days when an Human/Eldar Hybrid could become the Ultramarines Chief Librarian. Also, these were the days when the Ultramarines were a successor chapter from the 3rd founding, that had been founded to replace Legion XIII, who had turned traitor with Horus.
Rogue Trader was fun, but I appreciate that it's not a thing anymore. I'll completely rework the character. Would I at least be allowed to be the Tank-Hunter of the group, though?
Tank-Hunter is acceptable.
And I don't consider the weapons in Dawn of War as a viable source of serious canon, the overall plot though, I will take as canon. Just not the fluff about weapons.