As far as I know in Hellenistic Astrology the ruler of a house is the host for the planet(s) in that house - provided there is any. And the host is responsible for the well-being of that planet - in a way has to serve him/her - which is somewhat different from what people generally believe. I (so far not really familiar with these topics) have found that idea evident from the moment I came across it.

Well, VE (at 1 degree) LIB and SAT at 10 LIB - 4th house (whole sign).
VE is the host - but SAT has his special dignity in that sighn. So-who is the host, who has to "serve"? (I've come across this several times - this is just one example.)
LL