Obviously, the job is based off of the characters Squall Leonhart and Seifer Almasy from FF8.
All of Squall's other LB Finishers appear in the GNB's kit (Rough Divide, Fated Circle, and Blasting Zone).
What better way to honor the legacy of the character than naming Gunbreaker's LB3 "Lion Heart?" It refers both to Squall's final LB Finisher as well as the name of his ultimate weapon.
Thank you for your consideration.