Warthur
Saor's sort-of second sort-of first album (Andy Marshall, the man behind this one-man project, put out the preceding Roots under the project name of Àrsaidh before changing it retrospectively to Saor) offers a really nicely judged blend of atmospheric black metal of the most epic, sweeping sort, and carefully chosen aspects of Celtic folk music.
There's lots of folk/metal blends out there, but I find that a lot of them leave me a little cold because in coming up with the mixture the projects in question don't show much judgement when it comes to what to leave out, which I think is a mistake. Trying to incorporate all the metal and folk tropes and instrumentation into a composition at once just leaves you with a mess; instead, Marshall selects his folk incorporations carefully, a whistle there, a viola there, a bodhrán drum over there, and makes sure that the folk inclusions serve rather than disrupting the atmosphere thus established.
That said, this does mean it can tend to stray into the other pitfall of folk metal bands, which is that the "folk" bit is a bit of aesthetic flair tacked onto fairly straight-ahead metal. In addition, the mix is such that the non-metal instruments are often rather buried here, as can the vocals.