Cross-class ability choices

[Hundred]

The PLD would use Savage blade for the exact same effect however which is why Im saying it doesn't make sense to use.
Savage blade is 100 potency without a combo.
Skull sunder is 100 potency without a combo.
The enmity either generates without being used in a combo is the same.
If you are a PLD and use Savage blade outside of a combo you'll get the same enmity as using Skull Sunder in that situation.
If you want to get enmity faster without using Fast blade as a PLD then you can just hit Savage blade, it would give you the exact same effect as using a cross-classed Skull sunder in that situation. The two skills are copies of each other with the only differences being 1) animation and 2) The pre-requisite to count as a combo.
If you dont have heavy Swing then Skull sunder is always the same as using Savage Blade without Fast blade so then why would you use Skull sunder? You wouldn't.
If anything the reason PLD has skull sunder and WAR has Savage blade is just the mechanic they set up. The two skills are available to all classes and since both Jobs cross-class with the others main class they have access to it as a result of formality, they aren't useful.