Confidence is an Offensive Upgrade.
It is a special upgrade that does not have the Equipment version. User of this upgrade always does +10% damage to enemies, but his/her health is supposed to be reduced by 10% as well. However in the most recent versions confidence actually INCREASES health alongside damage, making it really overpowered and have no downside. Confidence is one of two upgrades in final slots of Calamity, Evelynn, Dex and Jyn. Also, you can get this in the slot machine.
Tips[]
It's not a very good idea to use this for low-health characters, such as Snipers, as it would reduce the already low health. It's recommended for Mercenaries, Juggernauts, and Elites, as they are the most tanky. But since it increases health it's actually a good idea.