YOu should try upselling or cross-selling along with those six fast-moving items on your online store.
I would say with regards to adwords its great that they are strict on the sword or weapon keywords this means their wont be much competition on it. Those restrictions only apply to your ad copy so you can still target the actual keywords, you may just word your ads differently yes you will get a lower quality score because you aren't using keywords, swords to weapons on your ad copy but I suspect with such low competition that wont matter. Actually having searched swords I see they are on search ads so google doesn't seem to have an issue with that word. Weapons may be another issue though.

I would also go to forums - I think that where a lot of weapon enthusiasts hang out because social media probably wouldn't allow this either, Ive seen a ton of gun forums so there will a few on medieval weapons out there.