BL’s son speaking:
Working from the Eluveite foundation, I would recommend exploring some of the similar folk metal bands from Europe. Bathory specifically on the albums Nordland and Nordland II (Sweden), Ensiferum (Finland), Arkona (Russia), Manegarm (Sweden) and Heidevolk (Netherlands) are all solid bands that play in a style somewhat similar to Eluveitie. If these prove interesting, you could try some more adventurous folk metal bands. Tyr (Faroe Islands) and Vintersorg (Sweden) both play great folk metal with some strong progressive rock vibes. The Irish band Primordial are also very interesting, but not so accessible. Their Celtic folk metal is very harrowing, very Irish.
Some bands approach folk metal with more of a black metal, neofolk, post-rock or darkwave thought process, preferring to be less straight-forward energetic and more ambient, atmospheric and moody. Moonsorrow (Finland), Agalloch (USA), Negura Bunget (Romania) and Summoning (Austria) are examples of this approach, though they all do it in a distinct manner. Not light listening, I will warn you, but quite rewarding if you have the patience for it.
If you’re interested in seeing how folk metal goes outside of the European style, you could try Melechesh (Israel), Rudra (Singapore, I thiiiink), Chthonic (Taiwain) or Rotting Christ specifically on the album Theogonia (Greece). They incorporate middle-eastern, Hindu, Chinese and Greek folk music, respectively.
There are a lot more folk metal bands to find, but this should be enough for now. If you like, you could try the Finnish bands Finntroll and Korpiklaani, who are fun in moderation but a bit too sugary and fruity for my tastes.
Hope you enjoy.