It's very lesser known because I only see it defined as such in medieval based video games, but "chamber" can also mean the act of defending by meeting the opponent's attack with your own. Mordhau and Mount & Blade use the term this way. On top of that, it could be alluding to chambering wind magic like a gun chambers bullets. I think "Sylph's Chamber" can make sense, but only if you know about the defensive tactic described above (since daggers can be dedicated to parrying).