If you send a young character to sparta, he can take part in the spartan Agoge and become a pretty tough guy.

Some of your FM, who could take part in the spartan Agoge, are that good, that they can even take part in the Krypteia. This means - as the advisor will tell you - that you should place him outside sparta, but still have him not leave the province for a couple of years. Just leave him there, same as the Agoge-procedure.

If he finished, he will even be tougher than the normal Agoge-Fellows