Since swag generally means the coolness of a person (e.g. I have swag, I am a swaggy person), would mojosegeco or mojoseco be a good translation for swag?
I’m not super hip with the lingo of today’s youth, but I’ve heard that swag comes from swagger, which is a verb that is translated to Esperanto as paradi or pavi (literally “to peacock”). If you wanted to maintain that connotation, you could use parademo/pavemo, paradeco/paveco, ktp. That implies a degree of arrogance that the word swagger carries.
Otherwise, mojosa seems to be the catch-all for positive slang terms. Lernu lists 'cool', 'awesome', 'groovy', 'radical', and 'epic'. To turn that into a noun, you would use mojoseco.
Very simplified, swag has two meanings
- not cool (because it is forced)
depending on context. Therefore, I would translate swaggy into mojosa or mojosaĉa/malmojosa depending on which of the two meanings is the intended.
It seems to me that you're piling slang upon slang and the expense of clarity.
Urban dictionary defines "swag" as... well... as a word that respectable people don't use. (Their definition was much more colorful than my summary here.) On top of that mojosa is widely overused - especially by new learners and anglophones who don't understand that "cool" means many more things in the English speaking world than it does in the worlds of the other languages which have borrowed this word.
Take a look in a thesaurus and find another word for the idea you're trying to express with "swag" and ask about that. It would help if you put it in context.