I don't know everything for sure (so others feel free to chime in if you know this in more detail), but you can try activating the cheat menu under the "Camp"-menu (and I think "Enhanced Options"), and there might be some item spawning there after you activate it. Other than that, you should check out the weapons for sale in the most relevant factions (this can be done more "legitimately" without cheats too).

Lastly, joining our Discord to get answers for questions such as these is always a good idea, all the people there with experience in game make for a knowledgeable group to ask for any Warband and/or Anno Domini 1257 related questions.