Well, the story behind the sabers is not very
complex but here goes:

Some Jedi were worried that if an enemy got his
hands on a saber he would be able to turn it
on with the push of a button. To avoid them
stealing sabers they devised some proto-type
sabers that would only activate with the use
of force on the energy crystal. But they had
to get special crystals that could be made to
only accept a certain "force frequency", then
they found what they were looking for. But
the crystals formed in spheres, so they had
to make sabers that accomodated the new crystal
structure. Thus these are the three that were made,
unfortunantly they were much harder to make
than the conventional sabers... so they ended
production and confiscated what few they could
find. You are lucky enough to have the three in
your possesion. Use them wisely.

Note: Just imagine the "force fequency" as a 
Finger Print that every Jedi has, each different
and unique. (my creation, not Raven or otherwise)

Note 2: if you do not like the idea, then don't
beleive it... it's not like it was made by George
Lucas or anything...