[Phantasm]

It's worth noting that a lot of technology in the old EU (current Legends) is effectively Precursor tech that the Republic and Empire don't know how it works or how to replicate it. In addition to the afore-mentioned Iokath, there's Centerpoint and Sinkhole Stations (the former yanked planets from across the galaxy into the Corell system, and sits at the point of gravity between two planets that orbit it as it orbits Corellia's sun; the latter keeps the Maw, in its EU incarnation as a black hole cluster, from collapsing in on itself), and the Rakata transporters on Belsavis. Not to mention exogalactic tech like the Vong biotechnology.

Just because it exists in the EU doesn't mean they (still) know how it works, after all....