I want to make my actor be more durable to hits, and i dont know what .ini stat will affect that.

He is a remake of a dummy but is to become a hit tanking unit.

And dont tell me increase his health, it doesnt look nice.

I need a defense stat!

In what way is he not durable enough, he can't take many hits, or he can't take hard hits (or some combination of the two)?
The number of hits the actor is able to take is governed by the GibWoundLimit of the actor's parts (head, torso, legs, etc). The number it's equal to is the number of hits the piece can take before gibbing, increase it to make the pieces able to take more hits.
The hardness of hits the actor is able to take is governed by the GibImpulseLimit of the actor's parts, the number is equal to the impulse (force per unit time) that the part can take before gibbing. Heavy or fast-moving partiles will have larger impulses, so if you want the actor to be able to take more of those, increase the GibImpulseLimit of all of it's parts.
An additional factor is the damages on the wounds for the actor. When a particle pierces a part of the actor, a wound is formed (which emits all the blood etc), these special AEmitters have BurstDamage and EmissionDamage that reduces the health of the actor on every burst (for wounds, when it is first created) and on every emission (when it spurts or w/e). Create custom wounds with lowered Burst and EmissionDamages to increase the health durability of your actor.