I mostly specialize in War gladiators and war hybrids, and thus have a few observations.

Create Distance seems to work best with slower weapons

Cannot Defend effect in general and in war cry, seems to only be effective against parrying gladiators.

Regarding Create distance I first believed intelligence and maybe even weapon length was the main factor in triggering Create Distance often. While intelligence may still be a factor. I scratched the idea of weapon length being a major factor when a rapier (a weapon with similar length to a bastard or long sword) triggered as much as a dagger which is very infrequent. A Bastard sword or Long Sword seemed to trigger it a moderate amount of times along with axes or maces. Two handed weapons triggers Create Distance the most with heavy Pole Arms right behind them. Spears may trigger close to Bastard Swords in terms of frequency.

Using Quick weapons on a war like daggers or rapiers seemed to struggle with activating Create Distance against their opponents.

War Cry seems to have little or no effect against gladiators who can dodge. The Cannot Defend effect looks to be only useful against attempting to parry, and in such cases will be a noticeable drop in the opponents parrying capabilities.

Against rage gladiators with dodge or shadows with dodge it seemed to have almost no effect against their ability to dodge attacks. Stun still seems useful in lowering a gladiators defense, however a stun on war cry is very unreliable.