It certainly reads to me as if it's a 'shield' that gives pretty much no defensive value, and can be detonated in two ways, either on a target surface using magnets or adhesive, or in combat against a target using Exotic Weapon (Blast Shield), accuracy 4.
In practice it's mainly effective as a way to breaking through a surface with minimum setup time, as it's hideously expensive for a one shot combat device.
It's a walk up, push onto wall, move back, detonate, walk through new door, device.