Hmm, well best i can come out with is, Aiming at the eye (with a sword)
or an Oath like an oath of office
seigan - oath
seiganken - oath of office
so it could be either
if you look at seigain as sei, gan
you get something about strength or military and gan doesnt give anything at all.
so i guess its more of an oath,
in what context is it being used?
Aikido faq lists it as
(Natural step, fundamental kamae.)
so i'm thoroughly confudled, why couldnt the japanese have ONE alphabet instead of 3?