Hello. I'm not going to join but I'd like to give you a piece of advice, that you don't have to listen to. Footman and Infantry are very very similar I would change Infantry to something else. a good fitting one is Man-at-Arms.
Your rank structure could look as such
Novice -> Recruit / Conscript / Yeoman -> Footman / Militia / Infantry -> Man-at-Arms / Lancepesade (this was a common term for a veteran in the medieval ages, deriving from an Italian phrase meaning broken spear.) -> Sergeant / Sergeant-at-Arms / Second Lieutenant -> Lieutenant -> Captain.
The ranks could continue but a lot of small guilds / clans get too large a list of ranks and then no one knows who's higher up and what not. I would stick to having 5 ranks or so until you grow into a large guild / clan.
Also I think that the rank of Novice should not be used because you should never accept someone into the guild / clan before seeing them fight, or talk you don't want to many trolls in your clan.
That is all I have to say hopefully some of it helps but remember you don't have to listen to me.