I would like to ask if we have informations about gol been a df user or been like garp without one
There's no confirmation of him having/not having a devil fruit. It's assumed he didn't, but until we get a concrete and detailed flashback, then anything can be speculated. Besides the chapter 0 encounter with Shiki, we've not seen him fight either.
Isn't there anything in the databooks or SBS about Roger's power or how strong he was?
Certainly the databooks must have info on him! After all, Oda did write the databooks! It'd be bad if he didn't give us complete information and risk spoiling us! DAMN YOU ODA!
Mocking of databook users aside, Roger for the most part is unknown. All we know is that he had the power to hear or understand feelings or things. We don't know how good a fighter he was (assumption is that he was a pretty good fighter to have been the captain and the pirate king, especially given what Rayleigh showed in his old age), nor do we know whether he had any devil fruit or not.
I'm gonna be emotional, man. I'm very upset that I get insulted because I actually realize databooks aren't the most accurate source of information, but I get attacked regardless.
Dunno, but it depends on the fruit he ate. If it's a fruit that provides armor and nothing else, then the sword and pistol would help. His devil fruit could also add extra power to pistol like that booger explosion guy's devil fruit did to anything. I just don't think we should write off the possibility of him having a devil fruit just because he didn't use it.