A small metal plate attached to a knife handle for decoration or as a place for an inscription.  Shields come in many different named shapes. See chart of shield shapes. On a fixed blade knife, the shield is called an “Escutcheon.”
Types of “Crest” shields
Types of “Bar” shields
Types of “Oval” shields
Types of “Gimp” shields
Variations of “Gimp” shields. Style at left is called a “Propeller Shield”, the other two were both used by New York Knife Co.
Types of “Figural” shields. Figural shields are popular with collectors and often enhance a knife’s collectibility. Let to Right: Bull Head Shield (Western Cutlery, Utica Cutlery, others), Doghead Shield (Union Cutlery / Ka-Bar), Keystone Shield (Keen Kutter / Simmons Hardware), Bullet Shield (Remington), Acorn Shield (Remington), Star Shield (Schrade Cutlery), Diamond Shield (Diamond Edge / Shapleigh Hardware)