[Eraqus isn't sure how specific he should be or not...it's a little difficult to explain without seeing it in action. That, and he can't help thinking back to such events with his own students.]

I suppose you would say it is a literal rite, performed with the Master's Keyblade. The apprentice needs to touch the Keyblade, and the master needs to promise through words and intent the inheritance. If both accept it, in time the apprentice gains the ability to summon their Keyblade on their own.

It's a very personal event, for both master and student.