Why don't Paladins have any unique "Cures"

[Enkidoh]

If you read Ishgardian lore, you know that every house's Guard is made up of Knights. Even their shields have their house logo. The Coliseum is attached to the Gladiator's guild, where warriors from all over come to prove themselves.

Rage of Halone is a Gladiator Skill, not a PLD Job skill. It could have been adopted by the guild if it was proven and tested in the Coliseum. Where an Ishgardian is more than welcome to participate in and where the name most likely came from.

Also if I remember version 1.0's lore, Lulusu at the Colosseum during the original 1.0 GLA class quests stated that Rage of Halone was a special skill originally used by the infamous roegadyn GLA Greinfarr (which was also known as 'the lost blade technique') - it was his special move that became synonymous with him.

So the actual name doesn't need to have any connection to the Guild at all, it was simply a name a specific character gave to that attack, and it became known by that moniker from then on.