Naval officers are a varied lot in terms of their college educations; wardrooms having a healthy mix of English, History, Literature majors among the BBAs, Engineers, and the like.
So, the topic of naval lingo will crop up in bull sessions, or in those quiet spots between tasks.
Having heard--and participated in--many of these, I ascribe to the notion that the verb came first, that naval miscreants were "brigged." Whether that comes from a sense of "razee-ing" the seaman from a full ship to something cut down to less; or from being put among brigands, I've no firm answer.
The way English will transmogrify verbs into nouns is far too well demonstrated to fuss much over.
That, and the verb sense is still in use, too.