While open market has a viable, if limited, selection of ballistics and missiles, the only energy weapon I have seen is mining laser, and even that is too rare (and too underpowered).
Mules are sold in open market, but without any energy medium weapons available (until player befriends a faction), player either needs to loot one from pirates or go to a black market. Without a medium energy weapon, Mule is worse than other freighters.
Since mining laser is open market, I suggest adding mining blaster to the open market. Where are miners getting their tools-of-the-trade? Military? Black Market? Also, maybe add a few others like (red) PD and/or tactical lasers.