In the forerunner saga, it says the domain, created by the precursers, contains 100 billion years worth of knowledge. The universe is about 6 billion years old, i believe. The only reason the forerunners managed to wipe them out is because the precursors didn't fight back. Then a single precursor managed to defeat the entire forerunner civilisation in revenge. I wont bother explaining how op forerunners are as its been explained. In the hypothetical halo v. Star wars fight, the precursors would fight, with 100 billion years worth of experiance. They could then proceed to share this with their allies, the rest of the halo universe. This would make up numbers, meaning even the weakest of people could be boosted beyond spartan level, probably beyond forerunner level. Im guessing they could probably build weapons that make the rings, capable of killing everything in the galaxy, look like spud guns.