Signet of Capture...WHERE?

I need some help looking for the signet of capture cus I want to try and get the elite skills (thats what I have heard it does).

Quarrel Falls from the skills guy.

There is a quest in Lions Arch also.

henge of denravi also has them scout keira I think her name is when you first talk to her she says she is watching you talk to her again and a option to teach you skills

You get your first two for free from Magi Malaquire in Lion's Arch. After that, you can buy more of them from him.

My question is, why is he called Magi Malaquire when there's only one of him? ("Magi" is plural: one magus, two magi.)

You can either get them from Magi Maliquere or you can get them in Quarrel Falls from the Skills guy. You can buy numerous ones from the Magi in Lions Arch though...