Swagger's full mean is something like the following:
Say, we have Luxray knowing Swagger against a Dragonite.
Luxray: You are nothing more than a c** of s*** which cannot even attack a Patrat, you are not more than an a****** without any brain, you are a foolish being that doesn't even earn the right to live on this earth !
Dragonite: Wut?! Dwarf** Grrrr***
Dragonite is getting enraged by those vulgar terms, so it get its attack up to be sure to kill Luxray, and this is so strong that Dragonite is getting confused of that strength ... if you see what I mean.
I implore everybody who read this not to think that I am a vulgar person, because of the words I used. This is just for really explaining what does Swagger do. You would be angry if I used this against you, no ? I would even be banned. Please, really, don't think its an offense. It this is even to much, I'l hide my answer. Thank you for your comprehension. Really.