One of my top favourites:
Excalibur, 1981
Arthur: Swear faith to me, and you shall have mercy! I need battle lords such as you!
Uryenes: [scornfully] A noble knight swear faith to a squire?
Mador: [shouting] NEVER... NEVER!
Arthur: You are right.
Arthur: [Hands Excalibur to Uyrenes and kneels] I'm not yet a knight. You, Uryenes, will knight me. Then as knight to knight... I can offer you mercy!
Merlin: [Alarmed] What's this? What's this?
Mador: Keep it, Uryenes!
Uryenes: [hesitates and then touches Excalibur to Arthur's shoulder] In the name of God, St Michael and St George, I give you the right to bear arms and the power to meet justice!
Arthur: That duty I will solemnly obey, as knight and king.
Merlin: I never saw this.
Uryenes: Rise... King Arthur.
[Uryenes kneels before Arthur]
Uryenes: I am your humble knight, and I swear allegiance to the courage in your veins. So strong it is, its source must be Uther Pendragon's. I doubt you no more!
[kisses Arthur's hand - other knights also kneel]