Because no one tells it, how do i counter this and for what i have to looking for?
It usually goes like this:
1) Enemy facehugs you.
2) Enemy starts a sideswing, and strafes in the same direction as the swing.
3) After getting blocked, the enemy immediately starts a swing in the opposite direction, and switches strafe directions.
You can tell somebody is probably going to castor from steps 1 and 2.
As a 1h, you can counter it by strafing in the same direction of the second swing (away from the weapon), and either left swinging or overheading. If you left swing, start the swing as close as you can to his head without risking a glance.
Alternatively, if you're good at kicking (I am not), you can kick him.
As a side note, this actually creates a pretty interesting mind game. The counter to the castor is pretty easy to chamber (being an immediate swing), so the castor footwork can be imitated to trick your opponent into an easy chamber. Cyranule is the only person I've ever really seen do this.