I think all 4 traditional symbols fall under this category.
DKM is part of a longer older mantra. Which if I remember correctly does have the attributes you describe.
I do know the more traditional understandings of the symbols have deeper meanings than we are usually taught in the west.
I do not however agree that one has to have the patronage of these particular deities.
I have heard it said that originally when Usui Sensei developed the system there were more levels than what we have now. What we have now was these levels condensed more or less. As time went on the number of levels lowered. But it has been said that the highest level in this original system was a step over Usui himself, because he believed it possible someone could transcend his own accomplishments. It is also said noone has reached where Usui Sensei was at in terms of spiritual development ( well no practioner of Usui Reiki Ryoho anyways).
But i think alot of this has to do with overmystifying the man that was Usui. He was the creator of the system and hence in the eyes of others i find it unlikely anyone will ever transcend him because in our minds he is often elevated to a status we often view as unreachable.
A;sp we know that Usui did not create the symbols. He chose them. they existed before Usui Reiki Ryoho. So perhaps this has to do with the deeper esoteric meanings behind the symbols, but that is not neccessarily the intent of Usui Sensei himself as far as the deific connection. Who knows on that aspect though.*shrug*
