is there a mod like a spar mod and it wont let you fall down?

No I dont think there is, the realtoriboxing mods have a kind of weeble effect, but its still possible to fall.

To be honest it doesn't sound possible as the mechanic's implimented to keep you standing would hinder the attacks fluidity of a real spar scenario.

The whole idea of a spar though is for you to stop yourself falling down.

Thank you cause i saw some toribash videos and there moveing all over the place and never fell to the ground

and every time the stand the just wobble.