Initiative is not speed. Speed lives in Melee, in the hands and feet that Dexterity and Agility supply. Initiative is nerve and judgement under violence — the willingness to commit, the discipline to hold, the clarity to see what is actually happening while it happens. Everyone has some animal instinct for it and may test it untrained, but it grows through training and, far more, through having been in fights.
The skill carries two rules of consequence.
Initiative Rank. Combatants act in order of Initiative Mastery Level, highest first. The rank stands regardless of how badly wounded or how badly frightened the character is; it is what they brought to the fight, not what the fight has left them.
Morale. At intervals a battle demands an Initiative test to establish whether a character is still in it — most often after watching allies go down. That a high-Initiative veteran might break where a nervous recruit holds is improbable but not impossible, and the rule is written to allow it: what the psyche does under violent stress is not perfectly predictable.
Shock is a subskill of Initiative — the body’s counterpart to the mind’s steadiness — with its own Skill Base of Strength and Endurance but Initiative’s Skill Multiple.