In FFXI, player affiliation to an organization (linkshell) can be seen by looking at the colored dot in front of their name.
But in FFXIV, I'd like to see a more visible type of marking. For instance, shields could carry the symbol of the guild, but it could also adorn special patches on pieces of armor or ornamental equipment such as signet rings, tattoos or capes.
To limit extensive disk usage with myriads of different emblems, each coat-of-arms would consist of a few layered icons. Each layer could be given their own color to enhance uniqueness.
* 2x2 checkerboard (red&blue) background with crossed sword&staff
* two-tone bullseye circles with an icon representing one of the city-states
* roaring lion on a field of green
Since SE would have full control of the generation of these emblems, they could be developed and scaled to fit any piece of armor or weapon without degrading quality.