Accuracy is NOT reduced by moving and jumping. Accuracy normally decreases by moving and jumping, and with Nervous Flaw (also Evelynn's flaw) it is reduced even more. This upgrade can remove that flaw. If you don't get it by leveling, you can get it from the Slot Machine and stack it to your mod slot instead of Equipment to eliminate the flaw. This upgrade doesn't have the Equipment version.
Nathan, the Engineer can have this upgrade along with two other upgrades that improve accuracy.