@VL7:
I wonder why the Behelit still hasn't ditched Guts group, Flora told them it was beyond mans control and if it wasn't meant for him it would get away from him no matter what. Guts would never use it and he's a sacrifice anyway so he probably can't, but maybe someone else from his group is marked by casuality.
Or maybe it is meant for him and it just isn't the time for the Behelit to be awakened. I mean Griffith had his for years, and it never fully awakened until a certain moment. Because as strong as Gutts is right now, there's no way he can take out Griffith. Later on Gutts will probably be tempted to use the Behelit and sacrifice his companions in order to gain enough power to challenge Griffith.
Although another way seems to be however Skull Knight has gotten as strong as he is now, and that seems to be the path Gutts is taking to gain strength to take out Griffith and the Godhand.