Individual combats and courtesy
By the way as [Sir Dinadan] rode he saw where stood an errant knight, and made him ready for to joust. Not so, said Dinadan, for I have no will to joust. With me shall ye joust, said the knight, or that ye pass this way. Whether ask ye jousts, [said Dinadan] by love or by hate? The knight answered: Wit ye well I ask it for love and not for hate. It may well be so, said Sir Dinadan, but ye proffer me hard love when ye will joust with me with a sharp spear. [Dinadan then proposed that they meet at Arthur's court and have the joust there.] ... Well, said the knight, sith ye will not joust with me, I pray you tell me your name.
Learning it, the strange knight said he knew Dinadan for a good knight and agreed to call off the joust entirely.
A trial of arms seems to have been almost as common a method for two knights, meeting by chance, to greet each other as a hello and a handshake. The perplexing rule, which seems standard, of jousting first and asking names afterward could lead to tragedy, especially when knights so often traveled with strange, blank, or covered shields rather than their own; nevertheless, it seems to be an outgrowth of a more general precept of etiquette that frowned on exchanging names too quickly.
For instance, Sir Bercilak and his people welcomed Gawaine into their castle, unarmed him, offered him a choice of indoor apparel, assigned him a chamber and servants, and brought him to supper, all before asking him - by hints and subtle, delicate questions - his identity and court of origin; Gawaine did not ask his host's name until after the beheading contest, when host and Green Knight were revealed as one and the same.
Sir Lamorak, adventuring anonymously, outjousted and unhorsed both Palomides and Dinadan, "but their horses he would not suffer his squires to meddle with ... because they were knights-errant". This, however, may have been more Lamorak's generosity than common practice. Strictly speaking, the arms and steeds of the defeated knights probably always belonged by right to the victorious opponent, but in friendly encounters the victors, especially when Round Table companions or otherwise notable for honor and courtesy, seem generally to have waived their claim. The defeated combatant also seemed to owe his service and allegiance to his conqueror; this rule seems always to have been applied when the victor was of Arthur's court and could thus gain his opponent's allegiance for the King.
for the love of my lord [Tor] of this castle I will neither hurt you nor harm you, nor none of your fellowship [said Berluse]. But wit you well, when ye are past this lodging I shall hurt you an I may, for ye slew my father traitorly. But first for the love of my lord, Sir Tor, and for the love of Sir Lamorak, the honourable knight that here is lodged, ye shall have none ill lodging.
It appears that castles and the rules of hospitality could serve as well as a church for sanctuary.