Swashbuckleptomaniac

Swashbuckle.
Kleptomaniac.
Swashbuckleptomaniac.

Someone who can't help but steal swords from pirates.

Which usually requires having a sword and excellent swashbuckling skills to begin with.

But how do you acquire those without already having a sword?

It's a bit of a double-edged sword.
(A double-edged sword that the klepto would first purchase, in order to avoid this circularity.)

Blade.
Adept.
Bladept.