I'm assuming it's a bug, because once you upgrade the shop, there should be a bow and two shields available to purchase. And since weapons are unique and finite, the merchants are the only way to acquire them.

I had something similar happen in my save. Before the latest patch, all merchants had two shields and a bow for sale. I had bought the bow and held off on the shields since I rarely use them, but now when I look in their inventory one of the shields that was available is missing. I think the newest patch had something to do with it because they did as categories for the customization items.

Yeah I noticed that when I installed the update, the Drekar Shield at the merchants is gone. It really sucks because the game is genuinely gun but the constant glitches I've had to deal with for +50 hours is ridiculous.

I just installed the new update about two hours ago and noticed that when I went to a merchant, one of the two shields they sell is missing from their inventory. Its the Drekar Shield. I noticed that the tattoos and customization schemes are now organized by categories so I wonder if that reworks is responsible for this bug.