The only thing you actually need is Shield Warden, Shield of Reckoning, and Divine Reflexes. That's it. Shield of Reckoning works great without anything else (in legacy Expand Aura and Security didn't exist and it was good without any of that).
Quick Shield Block is also good since its reaction is explicitly able to be used for Shield of Reckoning (and also Shield Block if they're targeting you). With that and Divine Reflexes, you have 3 reactions. I'd take that personally.
Greater Security lets you do it from farther away if it's the person you cast Shield of the Spirit on so it's nice. I'd definitely take that over Devoted Focus (which you don't need unless you're in a time-compressed situation and the rest of the group isn't making you wait a half hour to refocus three times anyway).
Expand Aura doesn't seem that necessary for this unless the person you want to cast Greater Security on is going to be a long way away from you when you want to put it up. If it's another melee character it's unlikely to be that critical. So you can delay that if you need to delay something.
So for all the other stuff, you're going to have to prioritize what matters most to you since you don't have enough feats to get everything.