Team Fortress 2 unlocks: Demoman

1- Main Weapon: Hand Mortar – Similar to the Grenade Launcher, but the grenades explode in contact.
• Pros: used to “bombard” the enemy lines. Helps the Demoman to manage short range combat better.
• Cons: lost of the bounce feature.  

2- Secondary Weapon: Bouncing Bombs Launcher - uses the same Sticky Bomb Launcher, but now the bombs don’t stick but bounce (farther than the original Grenade Launcher). The bombs can be detonated the same way as before. 
• Pros: can be thrown at far distance (when holding the fire mouse bottom). Can reach very unusual places.
• Cons: lost of the ambush feature of the Sticky Bombs. Harder to use the bombs to jump. 

3- Melee Weapon: TNT - like in the earlier TF2 movies
• Pros: great for room cleaning.
• Cons: lost of the melee ability which makes Demoman even more vulnerable at hand-to-hand distance. Limited ammo (other drawback comparing with the melee weapon).

5- Hand Grenade: Democharge – I miss the massive explosions and the special destructible objects from the TF1. Maps with alternative routes, only opened by the Democharge, would add more spice to the TF2. The Democharge would take long time to explode and could be “defused” by an enemy Demoman just by standing over it for some seconds.

For general modifications to the Demoman class, I would suggest increasing the clip size of the Grenade Launcher to 5 or 6 grenades (look at the model, it was designed to hold more than 4 shots!) and to extend the ammo capacity from 16 to 20.