Well, I listened to both Alfablot and Huldufolk a few times on Youtube, and I have a few thoughts. The first thing I noticed was that the master volume seemed a bit low to my ears. Also, I feel that the kick drum is too loud in the mix, and the snare is too quiet. Guitar tone is good, though personally I would turn the gain down a hair so the notes in the chords you play are clearer. Overall production seems reasonably clean.
Another aspect of the songs which was immediately obvious to me was their length (Alfablot at 1:32 and Huldufolk at 2:40). Now, I know that these are just demo tracks, but you and I both know that the songs that bands in the atmospheric BM genre produce tend to be longer than usual (5 to 11 minutes is commonplace). Alfablot and Huldufolk are not quite that long. I'm not trying to tell you how to write your music, but personally, I would make these songs longer and more complex - even though they were short, they felt kind of samey.
My final point is "atmosphere." It's a term few can define, but nonetheless it is what sets atmospheric black metal apart from other similar genres, such as DSBM. I'm not sure what it is - maybe it's the lack of vocals, maybe I'm too used to expecting synths in atmospheric BM, maybe it's the relatively short song length - but whatever the reason, these two songs lack "atmosphere." Unfortunately, I can't really tell you what's missing, but I can say that I'm just not "immersed" in these songs the way I am in bands like Lustre, Somne, Idaaliur, Inexistence, Basarabian Hills, etc. Now that I think about it, maybe the secret could be as simple as adding more reverb. But that's for you to decide.