The Sommelier is a service provided in The Continental, they supply and suggests arms and ammunition.
A Sommelier is normally an expert in fine wines, offering customers advice on important matters like wine and food pairing. Naturally, a sommelier is one of the services provided by the Continental, only this particular wine shop is a front for a high-end armory.
That doesn't mean it's not classy, though. Through conversations with his clientele, the Sommelier identifies a client's “dinner plans,” suggesting just the right weapon pairing to properly complement every course, starting out with a light pairing of Austrian handguns, the Glocks 34 & 26, before moving to a more substantial AR-15, followed by a “bold” Benelli M4 shotgun, before wrapping up with a spring-loaded boot knife for dessert.