In Game Banners

[Ossie The Great]

The unit banners are located in Rome - Total War\data\models\textures. use photoshop to open them ( u need the dds plug in ) The unit banners are mip map so when asked chose display mip maps and there u go.

P.S I am not sure if this is what u ment but this will change the banners the units hold in the battles

[Kuni]

If you've followed this very easy to follow and helpful tutorial and still see default banners for your faction, it looks like you might be referring to the standardbearer's banners. You can change those banners by editing the texture for the standard bearer, one of the officers that can accompany your unit. Some other units may have faction symbols too, you'll have to scour through the unit textures, so this is by far the most tedious part of faction conversion .

the unit textures are found in data/models_unit/textures