Slightly-modified weapons are the weapons that are modified slightly from the original weapon in Counter-Strike Online. They are usually added with a new feature but still retain their original design with slight modification. Most of them were previously released in Bingo.
- Main article: Dual Uzi
- Main article: M950 Attack
- Main article: Power Falcon
This is the modified version of Falcon that does higher damage than the regular Falcon and is able to do one-shot-kill to enemy in close and middle range targets. It was released alongside Broad Divine.
- Main article: PJ MK3A1
This is the modified version of PJ MK3A1 that does higher damage and has bigger magazine size than the original weapon. When fired the enemy will be on yellow fire for several seconds, giving consistent HP damage. It was released alongside Tornado.
- Main article: Burning AUG
This is the modified version of AUG that has a grenade launcher attached. The grenade launched explodes 1 second after it is launched, splitting 3 smaller grenades that explode on contact.
- Main article: Sterling Bayonet
This is the modified version of Sten Mk2 that has a bayonet attached. It is able to do melee attack and if used frequently, the bayonet breaks and the user needs to hit the enemy with the broken bayonet. It was released alongside Red Dragon Cannon and Special Duck Foot Gun