Weapons in Mass Effect 2 are divided into 6 different weapon types and are the main way to inflict damage to Enemies and Bosses. All Weapons have 3 different attributes and level (I through X). Higher levels, imply a more damaging weapon, greater accuracy and longer firing periods before overheating in comparison of lower level Weapons.
There are many conventional Weapons you can use in battles, but not every squad member can use all the Weapons. When you chose your Class, you saw that you were limited to specific Weapons (although you can acquire Weapons training while on a specific mission near the halfway point of the story). Team members must follow the same rules. There are several weapon classes available to you and your team, with at least two weapon variations in each class
Aside from thermal clips, some squad members, including you, have special ammunition they can use that has an added benefit, such as fire damage, or is powerful against a specific type of enemy. You can find them in the Powers page.
Thermal clips hold a store of disposable heat sinks universal to all small arms. Instead of waiting for an overheated weapon to cool down, you can simply eject the spent heat sink and the clip feeds in a new one. This allows for a greater sustained rate of fire and more numerous impacts on targets. The HUD element in the lower left corner shows how many shots are left in your weapons thermal clip. The bar below this number is the progress towards expending your current heat sink.
You will spot thermal clips on your missions on shelves or desks—look for the reflection of the clip in the light to easily spot them in intense situations. Fallen enemies also drop thermal clips. When you pick up a thermal clip, all weapons are partially replenished, not just the weapon you are holding.
Mass Effect 2 Weapons Category
These automatic weapons strike a good balance between stopping power and accuracy. Assault rifles are commonly used by soldiers, but you can train Shepard on this weapon if the commander selects a different class.
These handguns are all-purpose Weapons that are effective even at long range. They are the most accurate and powerful Weapons outside of Sniper Rifles. Heavy Pistol's clips are small, though, and need to be reloaded often.
Sniper rifles combine long-range killing power with lethal accuracy. The trade-off is that they have a slower rate of fire than the other Weapons available.