Holding down the weapon's input charges the bow. Releasing the input shoots the bow if it has been charged for at least 0.3 seconds.
Shooting the bow just as it fully charges, indicated by a sound and a special visual effect, causes the shot to deal 4.26x damage (341 base critical DPS). The fully-charged state occurs at 0.5 seconds of charge.
The Blueprint for the Nerves of Steel is found at the tower on the end of the Ramparts. This secret area is not guaranteed to generate on all runs, and cannot appear if the Stun Grenade's blueprint spawns. If it does, the exit to the Black Bridge will not be located at the end of the map and is instead shifted to the left a little. There is a short, invisible platform between the blueprint's tower and the second-last one that allows the player to make the jump. The homunculus rune can be used to detect the platform's existence but is not required for the blueprint.