You mountains of Gilboa,
let there be no dew nor rain on you, nor fields of offerings;
For there the shield of the mighty was vilely cast away,
The shield of Saul, no longer anointed with oil. Bible

“no longer anointed with oil.” Most shields had at least some leather, and that was rubbed with oil to keep it strong and flexible.

Commentary for: 2 Samuel 1:21