A survival posture built on the honest math of edged weapons: you will be cut. Trained cover routes those cuts to the least catastrophic tissue.
A reflexive shape that protects the head and neck when the blade appears without warning.
The default cover is the shape your body assumes before the mind has time to plan. Elbows travel to ear height, hands cup the back of the skull, chin tucks, shoulders shrug hard.
It is a triage position, not a beautiful one. It routes incoming cuts away from the neck, eyes, and femoral line, and into muscle that can be repaired.
From the cover, drive forward and toward the attacker's back, not away. Once you are behind or beside them, cover becomes control: attach at the elbow, separate, or exit.