This is pretty cool, but from a hard SF perspective, evaporating a non-trivial region of existence is going to release immensely more energy then a little bit of hawking radiation.
Maybe if the collapsed matter/energy is shunted somewhere else it would help in the whole conservation of energy thing. Maybe these weapons create nasty explosions in another dimension. Might attract the wrong kind of attention...
The second effect of obliterating a fixed radius of reality if in an atmosphere would be a massive shock wave as the vacuum collapses. This would resemble an explosion whose energy would depend on the volume of the destruction.
For fun I threw some numbers at it. A 1 km radius sphere has a volume of 5.24×10^8 m3. A vacuum has VERY roughly 2kJ of energy per m3. So, ~ 1x10^9 kj - which is roughly .2kilotons. A good boom. Go to Comment