Well, as far as Gallia is concerned, I'd go for Solar Engineering instead. It's just my own opinion though. EFL could work too, of course.
Also, I haven't seen anyone mentioning the research departments of various factions. E.g., LSF RD&A (Research, Development and Analysis Department) is responsible for the development of the Avenger VHF. I'm sure they'd also develop some unique weaponry (probably based on more popular designs) exclusively for the LSF.
P.S.: Just a small addition. The Order, for instance, could rely on civilian weaponry designs, probably modified by the Order Science Division. OSD may develop their own light weaponry too.
La Famille de La Brise de Mer officially started as an arms dealing company during the First Gallic War, but the Brigands hold the larger part of the arms market.
Solar Engineering would more likely would be the arms producer of Gallia.
Actually Daumann lost many military contracts after the war, afaik most of the capships are made by republican. However we are still a major producer of weapons, and military vessels in a smaller scale.
The ring sells light arms, which is a big market for Daumann which we RP as being produced by Daumann Arms Division(faction rp, not lore), and is the main competitor of Detroit munitions; despite this, Detroit munitions keeps the upper hand in the House market. There are bar rumors from corsairs talking about Daumann weapons in the Omicrons, a few hunters too, indicating that Daumann focuses on the borderworlds market (mainly Omega/Omicron space) and maybe a few Edge worlds via third parties.
I believe reading somewhere that Solar engineering is a big manufacturer for the Gallic government, I suppose they also make weapons