I'm very surprised that you actually made a walking bot with pistons! Besides the centipede, no other piston walker bot I made could escape insane havocking. Piston walkers were then excluded.
I don't know how and why havoc didn't occur to your weaponless walker, though.
In my opinion, weaponized walkers can only work against other walkers. A fast wheeled bot will very easily push, flip and throw a walker.