So what I think you want is the DS9 era Klingon emblem.

Check out this eBay listing: www.ebay.com/itm/225629480900?mkcid=16&mkevt=…

According to this article this is the banner that was used on the Promenade in DS9. This is a “chair drape” (whatever that is) but maybe you could use it as a flag, convert it to a flag, or have a custom flag made based on this?