A type if shield actually wouldn't be a bad idea but it should break. It would be a type of handheld energy shield that after taking so much damage starts to falter allowing bits of damage to be taken and then eventually will discharge so no more protection. After a specifies time period the shield would be back online after recharging. And you should be able to peak around it making yourself vulnerable to an extent to shoot a pistol or smg. The shield would be a light weapon and the sidearms of pistols and smgs could be used with it. You could melee with the shield as well of course for maybe damage more than a normal melee but maybe not as strong as a nova knife. Better the operation skill the quicker it recharges after failure. And then skills increasing it melee damage and recharge rate when not fully depleted. Other than more strength and damage for standard to prototype you could add a tactical variant that would work as a flux grenade kind if where it is weaker but you can use its energy to knock down enemy shields or even a variant that temporarily energizes friendly shields for say 10 seconds and would give more shields a second based on whether it was advanced or proto.