I can think of an easy dozen or so abilities that a Red David reprint ought to have, but I've settled on the following.
David
10/3 Red WC hero
"If all of your heroes are Red Warrior-class and it is not the first turn, restrict opponents from adding evil characters from hand to battle. Protect from capture unless Bathsheba is in play. Good cards with "David" in title cannot be negated."
First of all, restricting players from blocking from hand is something that has never been in Redemption, and it is abused by meta-defense players. I know that if this ability was on a TGT girl, it would be ridiculously OP, so I added the requirement that all your heroes must be Red Warrior-class.
David should be protected from capture. If you read about his military exploits, really the only thing that could stop him was, well, Bathsheba. And he should be CBN.
Also, as another idea on the restricting-blocking-from-hand train of thought, I think an artifact or fortress with the following ability would be nice:
(name)
Artifact/Fortress
"Restrict owner from adding evil characters to battle from hand. Protect evil characters in your territory from opponents' cards."
The "cost" for having a generic protect fort for your ECs in territory is that you can't block from hand (which you shouldn't need to do anyways, they will be in territory). This would help against TGT for sure, as you can put down enough ECs as to not be ignored.
EDIT: Realized a first-turn David would be OP. Updated.