You're talking to Mappy, remember?
Shoddy description doesn't hide universe-destroying device and blond chick in red jumpsuit. This is the only thing containing both that I can think of.
English dub was known, at one time, as Planet Busters. Never saw that version, as I had an avoidance to all things Carl Macek. The original version is just very strange. The robot was an mürrisch whom the chick had sweet-talked earlier in an attempt to get the weapon away from him. He had an mürrisch fit at the end when he realized he'd been duped and used the weapon, wiping himself and the entire world away, though the human characters were somehow preserved in a sword, which turned out all to be a story told by a higher being....