The thing is though those weapons were on the Forward Unto Dawn (not the show) but the ship the Chief was on before it crash in Requiem, the Dawn was in service during Halo 3 and so that's my thinking of it. But it's not a big deal to me use the human weapons from Reach, 1,2 and 3. And the team is special forces so they should get their hands on better tech, there isn't that long of a gap between 2550-2557.