I think that idea would kinda be like playing Dark Age of Camelot (PC game) but i do like the idea of having your rank shown to members of your guild so they are impressed if your a high rank or laugh and taunt you if a lesser rank.
Yes, this would be natural to see a rank insignia of a guild and respond to it, and as we know that there are decals
Assuming there's a fair number of equipment slots, with some layering, I'd like to see different guilds give out specific clothing items that show membership and rank. I was thinking something like this:
Mercenary companies and knightly orders have tarbards and surcoats, to be worn over armor.
Illegal guilds, like thieves and assassins, have something more subtle, like rings or amulets
Mage and religious groups would have things that look good worn with robes, like hoods, shoulder capes, or scapulars.
Guild specific gear are nice, but creating one for each rank for each guild would be too much, but insignias that could be attached to any gear are cheaper to make.
But having gear that show two or three different ranks lower and higher ranks and maybe some special ranks with special privileges of some guilds would be great, like special capes for higher ranking members, and special capes and hood for some special members, and so on...
that sounds like a pretty cool idea maybe they'll do that. *fingers crossed*
Those ideas are not hard to implement, but when they are all or nothing, and could not be applied to a part of the game and ignored for the rest, so that would be a serious undertaking for the developers.