Two types of Damage?
 

Okay, so i am working on some stuff for a sort of Steampunk Fantasy game using 5th edition. i found stats for a Sword Pistol and Gun Axe on the 5e Wiki (Which has a ton of great fan-made stuff on it). so here are the stats:

PISTOL SWORD:
Cost: 85 GP
Damage: Blade: 1d6 Piercing, Finesse, Light
Damage: Flintlock: 1d10 Piercing, Ammunition, Range 30/90, Loading, Special*
*When you hit a creature with the blade you can use a bonus action to make an attack with the loaded flintlock against the same target. This is considered to be a melee attack.

GUN AXE:
Cost: 90 GP
Damage: Axe: 1d10 Slashing
Damage: Flintlock: 1d6 Piercing, Ammunition, Range 30/90, Loading, Special*
*When you hit a creature with the axe you can use a bonus action to make an attack with the loaded flintlock against the same target. This is considered to be a melee attack.

My Question is, How do i add 2 different types of damage to one weapon without using the Versatile options in the Editor?

Any help or ideas are appreciated