@CrimsonCW
I supposed it's possible Griffith redirected (or deflected) Guts' blow like he did with the Skull Knight at the end of Falconia, and the earth shattering when Guts' sword touches the ground is the actual force of his swing, but then there's the tree losing all of it's leaves and a lot of weird energy going on which seems more connected to the quake than Guts. I agree that it isn't entirely clear.
The way it seemed illustrated to me was that Guts is going in for a swing towards Griffith's back, then there's some sort of illustrated blow with the wind effect, indicting that Guts' sword was suddenly stopped, either by his own volition or Griffith's. However, the next page shows Griffith embracing Casca, with a bemused Guts. The page after that—the low angle with Guts' sword over Griffith's shoulder, with Griffith and Casca in the foreground—makes it seem like he stopped because it's clear the sword would have gone through Casca. After that he lowers his sword. Maybe if the Berserker armour had taken over, he wouldn't have stopped, which is why the author's made a point of retaining his normal self, which I found a bit odd given the situation.
Who knows, hopefully we find out a bit more. It can go either way. I think the art is pretty good, obviously not Miura-level, but a fine replacement, however the destruction scenes are a little messy and there hasn't been much dialogue yet.