From memory, (goodness knows why this stuff stays in my head all these years! :) there was a Lone Wolf Club Newsletter where Dever pointed out that in reality, during most of the magnakai quest, Safekeeping meant keeping items in Elzian, not the Kai Monastry.
-- David Davis
But, strictly speaking and even though the rules mention it, you do not start the adventure at the monastery. I cannot understand how you are going to put stuff under safekeeping at the monastery (specially the Sommersword) when you are (hundred of?) miles away. Are you going to entrust someone to take it to the monastery? What if he tries to combat with it during the trip and he is not a Kai lord? :-)
If it's your first adventure, you can use the Psychic Ring instead.
I find it striking, and so do people in the forum [1] that the Psychic Ring does not give you any bonus if you are using the Sommerswerd. Oh well... will replay with the Sommer in safekeeping next time.
Regards
Javier
[1] http://projectaon.proboards30.com/index.cgi?board=general&action=display&thread=1134636619