History of Foundry

A foundry (weapon foundry) is a weapon manufacturer whose products share a visual style and design philosophy. Destinypedia lists SUROS, Hakke, Omolon, Tex Mechanica, VEIST, Black Armory and Cassoid among others (also Daito, MIDA and Crux/Lomar).

Origin traits

Since The Witch Queen, each foundry has an Origin Trait attached to its weapons. Examples from sources: SUROS (reloading grants handling and flinch resistance), Hakke (extra damage to vehicles, turrets, barricades and Stasis crystals), Omolon (better reload and stability while the magazine is in its upper half) and VEIST (chance to refill the magazine on damage). Details may have changed with later updates.