The rare noun arshet refers to the utterance or request of the lips — the words spoken in petition. It appears in Psalm 21 alongside aresheth (desire of the heart), forming a couplet that captures both the inward desire and the outward expression of prayer.
The pairing of heart-desire and lip-request in Psalm 21:2 reflects the biblical understanding of prayer as the alignment of inner longing with spoken petition. True prayer is not mere words but the expression of deeply felt need. God's fulfillment of both the heart's desire and the lips' request in this royal Psalm models the responsive relationship God desires with His people — He listens, He acts, He provides.