Who to give Shield Pulse?

It's more about who has the "proper build" to even be able to run Shield Pulse. It's not really that much of a sought-after skill considering it's only for skills like Aegis.

I have 6 pity breaker Sabers, Fjorm is the only unit I have that runs shield pulse. I keep him around for slaying edge because even at +5 his stats aren't very good.

If you haven't already, give Ayra +Spd Slaying Edge, fundamentally better than her legendary weapon LOL

If you dont need slaying edge and need shield pulse, you could run a aegis a slayer weapon and dc and heavy blade it would run like this
Turn 1 get aegis rdy, get attack aegis procs
Counter attack with unit aegis is up again
If you got double your aegis procs again.
It will catch people offguard.