Instead I suggest that shields get actual weaponized effects as it would initially hint at.
Base shield could receive an emergency shield effect either increasing it to 1s or to be on both shieldbreak and full repair.
Amp possibly might double your current shield effect power if you are in a circle of the map that changes every few waves or so.
Siphon could uniquely have a normal enemy that spawns in highlighted and if you kill it with siphon you get 1% shield.
Maybe for Temporal on shield break or fix a slowing effect pulse outwards.
What might be good for Shockwave is to have the pulse on shield break as well or pulsing every 5s.
Warp should maybe have a small Death Blossom effect.
Halo might leave the halo effect where it broke until the shield fixes itself.
Bastion would mimic the Constructor enemy and orbit the player with smaller Bulwarks.
If Helix kills an enemy it returns X% shield/hull.
For reflect on shield break it creates a line that retains the reflection.