The stolen banner in The Blood of Dawnwalker was taken from Gremla's shed as part of the Blasphemy quest in the beginning, and she asks you to find it (and by extension the thief). This is one of the optional quests of the tutorial that's largely about introducing Focus Mode as a mechanic, the system by which you highlight and analyze objects of interest. Below I'll show you who took the Banner and how to find them, so you can complete the Blasphemy quest in Dawnwalker.
Exploring Laslea for the first time? Find out what to do before sundown in The Blood of Dawnwalker, or make sure you understand the Blood of Dawnwalker time mechanics so you know when it's going to pass.
When investigating Gremla's shed as part of the Blasphemy quest, the specific things of note that you need to scrutinize are the footprints around the back of the shed, and the bloody scrap of the banner that they lead to.
The odd footprints and the blood on the banner give you two clues about the thief: that they have an injured hand, and that they walk with a cane, which definitely narrows down the villagers. Of course, Laslea isn't a small community, and even finding the person who matches that description isn't easy.
The banner thief in the Blasphemy quest is Premysl, the old man found sitting by the farm at the Northeast side of town at the location shown above. He has both the right injury and a cane, and will break under the pressure of questioning if you talk to him. However, this leads to a reveal about what's on the banner, and the subsequent choice about how to handle it.
Premysl reveals that the banner is a monstrous presentation of vampiric butchery, which Brencis (if he gets it) is going to hang in the church instead of the cross. Premysl, a devout Christian, sees this is an unforgivable act of cowardice if they let it happen, whereas Gremla is just happy to make the banner if it means that Brencis leaves Laslea alone.
Of the two choices - telling Gremla that Premysl stole the banner or keeping the secret - I recommend that you tell Gremla the truth, but it doesn't really make a huge difference either way. She'll give you a small amount of money (25 Denarius), but without meaning to spoil, the consequences aren't really going to come up again in a significant way.
هەفتانە هەرسکردنەکان، چیرۆکەکانی ئەو کۆمەڵگایانەی کە خۆشت دەوێن و زۆر شتی تر
سەرچاوەی فەرمی بە زمانی ئینگلیزی: https://www.gamesradar.com/games/action-rpg/blood-of-dawnwalker-banner-blasphemy/
