I found the merchant bug! Thanks, I hadn't read your message carefully, but it's fixed now.
I also fixed the HP when merging. I noticed there were issues with the HP when switching amulets as well, so both bugs are fixed now.
Regarding an amulet to guarantee the blacksmith's durability, it doesn't exist yet, but it's on my to-do list.
I wouldn't want to just change lower attack to a block, I need dodges to exist so you get different advantages against enemies depending on the class you use.
new build will be up on few minutes.