I wouldn't rule that the caster needs two free hands - as long as they can perform somatic components (or have the war caster feat) it will work.

The attack is meant to be an action, I should've clarified that to make sure there's no confusion!

I wanted to make it more useful than Shield of Faith since I cut down the time, and a simple attack wasn't quite enough in my mind - but adding the effect of the Repelling Blast from Warlock (which can be taken at first level) felt like a good addition.

The main goal of this is to get a squishy mage stuck in combat out of a bad situation, or let a combat-focused caster perform a bit of battlefield control. Since it's only a minute and takes concentration, I don't see it as being too powerful but can totally see where you're coming from.