Thankee on Arcane Mastery...I'd always planned on asking for it, but didn't think it'd be useful so soon!
As for the invocation, yeah, it doesn't work for all flavors of warlock, but unless we get a wizard Inamar would logically inherit magic item ID'ing duties. I could take the spell as a sorceror, but that introduces the hassles of expensive components which then have to be somehow traded for and kept track of...etc etc. In a more conventional game, it's not as big an issue...but I suspect the Dover village doesn't have a guy selling magic pearls for 100gp a pop like a lot of campaign worlds do.
Anyway, it's not a BIG deal. If you decide the ID invocation is too much, I'll take Identify next level as a sorc spell and something like Entropic Warding this level. Otherwise I'll take the ID invocation, since it expands her party role a bit and, as you say, suits her concept very well.