The encounter power is the main effect the player can't get in one slot. You can get the +50 Armor/Ward/Focus half if you take Rime Veil, or you can get the increase to threat generation from War Banner, but not both. Between the two I'd say Rime Veil is more likely to play out the way you want in practice, because the damage it contributes will generate threat on its own once it gets going, while the regen from the Banner probably won't keep you alive between healer turns when you're the healer. If a heal isn't coming until your turn either way, a slightly bigger heal on that turn isn't going to make as much difference as making sure that you live to see that turn. War Banner tends to be better the more staggered the tank and healer are in the turn order for that reason.
For the At-Will, Lay on Hands does essentially the same thing as Cait's.
In place of her Searing Aegis you have Shielding Smite, which is also a single target attack that gives your party +50 Armor/Ward/Focus on a 3 turn cooldown. Yours is both more spell damage and comes with weapon attack attached, but while hers attacks ward instead of armor and is a 50/50 fire/holy split while the spell component of yours is all fire. Yours does more damage to most enemies assuming your weapon is decent.
Instead of Sun of Jassira you have Flash Fire, which is also fire damage to a single enemy with a secondary magic attack to blind the rest of the enemies on a 4 turn cooldown. It's also over double the damage, can't miss, the blind lasts 2 turns instead of 1, and the blinded enemies are also burned for [5+Willpower]/turn. Burning enemies even take more damage from your Thorns if you decide to go that route, since it's penetrating damage. Pretty clear upgrade over Caits.