Sergeant at Arms
I think it would be a relatively easy and well-supported idea, To add the banners of all the previous Warband/Viking conquest/F&S and NW as Sigils in BL. You could have different tabs separating these sigils, each for their own game. The AI wouldn't have access to these sigils. I think it would be a really easily to implement idea as you already have all the textures needed. It would be great for MP and SP as it would give way more customization and personality to the sigils. And for people that don't like or enjoy using really out-of-place banners like let's say the Sweden banner. Because it would be only restricted to players it wouldn't really hurt or mess with anyone's "Immersion". This would also reward old players who had a specific Banner/Sigil they liked in previous games. And I don't really see the downside of doing something like this and it would be pretty easy to implement I think.