The Lord of peace himself (αυτος ο κυριος της ειρηνης). See 1. Thessalonians 5:23 for

the God of peace himself .

Give you peace (δοιη υμιν την ειρηνην). Second aorist active optative (Koine) of διδωμ, not δωη (subjunctive). So also Romans 15:5; 2. Timothy 1:16; 2. Timothy 1:18. The Lord Jesus whose characteristic is peace, can alone give real peace to the heart and to the world. (John 14:27).