Probably, because he uses that thing A LOT in fights if you look at it. Specifically, he uses it to help support his sword if he's blocking, so he won't fall off his feet. Example being when he fights Zodd in Volume 22.
Guts was just a really strong person to begin with, before the Eclipse stuff, since he trained at a higher level than whatever he was supposed to at his age. Living in the Interstice has just made him more attuned to that world and so he can see/touch all those things...that's what the manga...
Ah, is that the picture of Guts when he swoops in to save Caska from that weirdo cult sex group? Definitely a favorite of mine, it's like the best shot of Guts as the proverbial knight in shining armor.
If in fact Berserk was picked up again to become an anime series, I'd hoped they would just start it during the Lost Children arc and continue forth from there. But include Puck and the Skull Knight and everything that was excluded from the first series. Most people in Japan have already heard...