The thing is that the iconic game for the gunblade, FFVIII, doesn't actually have shooting or exploding with the gunblade. If I remember correctly how it worked, it didn't fire a projectile; pulling the trigger simply triggered the "shot," which set the entire blade to reverberating, and that vibrating blade inside a target being slashed through dealt critical damage by simply ripping through the target rather than a clean cut. You didn't fire an actual bullet--there was no projectile launched at all.
In that sense, Lightning's gunblade is the most true to the idea of a "sword that shoots as well."
