Gunblade
Squall is a gunblade expert. In battle, pressing the R1 button just as he's swinging down causes extra damage to the enemies. His limit break, which has an increased likelihood of appearing when his HP is low, is called Renzokuken. Depending on how advanced his weapon is, he can randomly do one of several limit breaks.

All weapons in Final Fantasy VIII are upgraded (modified) instead of bought. Certain parts and pieces of equipment must be in your inventory before Squall can upgrade his gunblade. If you already have the necessary equipment to modify the gunblade, when you visit a dealer, the weapon will be displayed in the store window. Otherwise, you can discover what equipment you need by reading the magazine Weapons Monthly. (Though all Weapons Monthly magazines except the 1st edition can eventually be purchased in Esthar at Karen's Shop, it's better to find them first since visiting Esthar occurs much later in the game.)

Revolver
Cost: 100, Attack: 11, Hit: 255
Limit Breaks: Rough Divide
Acquired: Default. Weapons Monthly #3: March Edition (defeat Elvoret in Dollet's Communication Tower)
Upgrade Equipment: 2 M-Stone Pieces, 2 Screws

Shear Trigger
Cost: 200, Attack: 14, Hit: 255
Limit Breaks: Rough Divide, Fated Circle
Acquired: Weapons Monthly #4: April Edition (found in Balamb Garden. Check Squall's desk in his new room)
Upgrade Equipment: 1 Steel Pipe, 4 Screws

Cutting Trigger
Cost: 400, Attack: 18, Hit: 255
Limit Breaks: Rough Divide, Fated Circle
Acquired: Weapons Monthly #5: May Edition (found in Deling City: using Rinoa, before you climb up the boxes, go down the manhole into the sewers)
Upgrade Equipment: 1 Mesmerize Blade, 8 Screws

Flame Saber
Cost: 600, Attack: 20, Hit: 255
Limit Breaks: Rough Divide, Fated Circle, Blasting Zone
Acquired: Weapons Monthly #6: June Edition (defeat BGHZ51F2 at Galbadia Missile Center)
Upgrade Equipment: 1 Betrayal Sword, 1 Turtle Shell, 4 Screws

Twin Lance
Cost: 800, Attack: 22, Hit: 255
Limit Breaks: Rough Divide, Fated Circle, Blasting Zone
Acquired: Weapons Monthly #7: July Edition (in Balamb Garden's Training Center, check the construction site)
Upgrade Equipment: 1 Dino Bone, 1 Red Fang, 12 Screws

Punishment
Cost: 1000, Attack: 24, Hit: 255
Limit Breaks: Rough Divide, Fated Circle, Blasting Zone
Acquired: Weapons Monthly #8: August Edition (found in Trabia Garden near the gargoyle)
Upgrade Equipment: 1 Chef's Knife, 2 Star Fragments, 1 Turtle Shell, 8 Screws

Lion Heart
Cost: 2000, Attack: 30, Hit: 255
Limit Breaks: Rough Divide, Fated Circle, Blasting Zone, Lion Heart
Acquired: Weapons Monthly 1st Edition (found in the Esthar control room)
Upgrade Equipment: 1 Adamantine, 4 Dragon Fang, 12 Pulse Ammos