I liked the premise with this one, especially the sort of 'double twist' around the ending and the nature of the 'weapon' itself. It gives a nice mystical air while still leaving things grounded just enough to feel relatable. The ending is both solid enough to be conclusive and open enough to make me feel like the story isn't over.
The writing is a little flat in places, I think chiefly because you're relying on telling, not showing. For instance, when Appleblossom first wakes up, don't say he was startled, show him jerking awake, maybe spilling half a tankard of leftover mead on himself in the process. Your descriptions of the various Shadow Stalker monsters were well done though: concise and effective, with just enough detail without being overwrought.
While I did enjoy the spin you put on alcohol as a 'weapon', you're also writing about an alcoholic using his dependency to cope with nightmares - I know it's a fantasy story, but your choice of enemy faction and weapon combined evokes PTSD giving rise to alcoholism a little too neatly, and the general tone could come across as approving alcohol as a coping mechanism. I can see where you were addressing the issue of addiction to an extent, but bearing in mind that alcohol 'saves the day', I'd still suggest focusing more squarely on the realities of addiction, even if with a stronger emphasis on the unreliable narrator angle.
I apologize if that got a little too heavy, but at the same time I couldn't leave it unsaid. I did enjoy the story overall. I liked the half-explained mysticism (mysticism is better half-explained!) and I think there's definitely room to write more of these characters.