For Honor Run then CLOSES. Uplay asking for ACTIAVTION KEY?
I just found a fix for For Honor that all you that are having these troubles should try, it worked for me and the other people I have told so far.
Close / exit steam. Then run steam as an administrator, sigh#n in blah blah blah. Click play on for honor. It should open uplay but this time uplay wont ask for an activation key, it will say your about to play for honor and you just click continue. Then the game launches.
Hope this helps