Velocity

Velocity is the speed of a projectile fired from a weapon. It is not to be confused with use time, which is how fast an item can be used (i.e. fast, average, slow). The higher the weapon's velocity, the faster the projectile travels, and the sooner it will hit its target. Likewise, weapons/ammo with higher velocities will reduce the need to "lead" shots ahead of a moving target in order to hit them. This is an advantage that may prove very useful when fighting fast-moving enemies or when attacking from a large distance.

Tips
Since the velocity of different weapons and ammo are not provided while playing, here are some basic guidelines to follow when considering the velocity of a certain item: Many projectiles have a sudden and significant decrease in velocity when impacting liquids such as water. Some projectiles, especially flame-related ones, are even immediately destroyed upon entering a body of water. In the case of most, if not all, projectiles, there is a "lifespan" that causes the projectile to disappear after a certain period of time has passed, regardless of the distance traveled by the projectile. This means that liquids can reduce the effective range of a weapon against enemies submerged in a large body of water, sometimes to a significant extent.
 * Weapons that use arrows generally have lower velocities than bullet firing weapons, but do more damage.
 * Certain ranged Modifiers can affect a weapon's velocity.
 * Some weapons (often magic weapons) don't have a consistent velocity.
 * The Demon Scythe fires a projectile with an exponentially increasing amount of velocity.
 * The Death Sickle's projectile is the opposite of the aforementioned - firing a projectile with exponentially decreasing velocity until it stops in place before disappearing.
 * The Magical Harp's note projectiles have a velocity based upon how far from the player you click when using it.
 * The Cursed Flames projectiles increase in velocity every time they bounce.
 * Magic weapons that fire projectiles cannot have their velocity modified.
 * Melee weapons that fire projectiles have their velocity increased by modifiers that improve melee speed.
 * Having a Velocity Modifier on a Flamethrower increases its range due to the time it takes for the fire to burn out

Bullets, some magic projectiles, and a few others are not affected by gravity, and will maintain their trajectory and velocity when shooting upwards as opposed to slowing down and eventually falling. This is a major advantage when firing at airborne enemies or across long distances.