User blog comment:Echo 1/UNSC Weaponry seems unrealistic/@comment-1819700-20100714221037

Presumably, the Covies got the tech for their DEW's from reverse-engineered Forerunner relics and since they have the Huragok (which were created by the Forerunners) they could have done it quite easily. The only Forerunner objects truely in UNSC possession was Onyx but they never knew about it until later and that crystal until Locklear blew it up. But seeing as there would be a ton of plasma weapons left over on earth, a possible knowledge trade with the Sangheili or perhaps messing around with the Portal the UNSC will most likely have DEW's after the war.