Messenger is still OP. Auto-win characters should never have CBI in their ability. Besides, all the guy did was come tell David that Saul was dead, and lied that he killed him because he thought that's what David wanted to hear, and then David killed the messenger because he confessed to killing the Lord's anointed one. Why should this character get such a great ability?
Also, you need to word these cards as cost-benefit. That way you can't use protect abilities to get out of a cost while still reaping the benefits. For example, Amelekite Raiding Party has a costless conditionless discard of a fortress. If Covenant with Abraham (lol) is active, he discards a fort, sets aside a hero (an opponent's, maybe even in the field of battle), and stays in battle, CBP. And he works as a hero. Better to have the set-aside part come first as a cost to receive the discard benefit.
Fall by the Sword, although a generic CBN battlewinner if used properly, I like. It seems to fit the verse well. And conditional CBN seems the way that Redemption is going right now. I'd make it Brown/Black and usable by Canaanites as well, as they are mentioned in the verse.