By which two acts did a vassal publicly promise loyalty to his lord?

Explanation

The two acts belonged together and were done in front of witnesses: the man knelt and placed his hands between his lord's to acknowledge the bond, then swore on holy objects to keep faith, so that others could testify to both later. The knighting ceremony is the confusion to head off, because it is the other famous kneeling ritual of the period, but it conferred a military rank and created no obligation between one particular lord and one particular tenant.