While on reddit I saw that someone posted asking if the FF13 Blazefire Saber could get updated to work for Gunbreaker.
The poor poster is being beaten into a pulp by the toxic Reddit community for making the mistake of asking a harmless question.

But, I agree with the poster. It IS a Gunblade, so Gunbreaker should be able to use it. It harms no one & it can be argued that it makes more sense for Gunbreaker to use it over Paladin.

Since that poster didn't think to ask on the forums I'll ask for him/her.
I'm not holding my breath on SE doing so but...it's worth asking cause the OP did say one thing that honestly hit me hard.
"If no asks the chances of it being updates remain a flat 0%."

That said:
"Can Gunbreaker be given access to FF13's Blazefire Saber glamour?"

While we're at it.
Can the BLM & WHM FF13 Glamour be updated to 2-Handed Weapons while we're it. You know...so they'll actually be usable?