User blog comment:Harold Burned-Mane/Beneath the Black Flag - Setting/@comment-24760123-20180416014134/@comment-17114085-20180417132028

You could use this one:

It's from the Beyond Skyrim mod team, they made it for their High Rock mod. Not sure what exactly it's for, but it's Imperial and rather intricate.

If you want to make it blue you could always just use photoshop to change the color.