Indie Metal.
It's definitely indie metal. Just in the last few minutes I've been reading about the band and watching some more of their videos. In all honesty, I don't much like the approach of that bassist. The sound he gets, especially on his new unknown bass, sounds as much like rhythm guitar as bass. Interestingly enough, the lead singer played bass for some bands before she started singing for that one. I'd like to hear her play bass. I bet that would be interesting. She seems to be very deep into music, for the sake of music itself and not for other people. I like her and also that lead guitarist. Some of their songs have a definite Middle Eastern sound. That makes them even more indie. I might add that I don't really mean to be critical of the bassist. He is definitely beyond me. Plus, there is nothing he is doing that is wrong. It's just I've always had a thing about wanting to distance the sound of a bass from a rhythm guitar. This goes back to my teenage days and I haven't changed on that.
Update
Finding this info was not easy. and maybe not too important. But this topic is about the RD. What I found out is that bassist for Messa isn't playing his RD much in public because it's his favorite bass and he doesn't want anything to happen to it. That's why in the concert videos I kept seeing him play something else which I'm pretty sure is a Kramer 8 string. I guess he doesn't care if that got damaged in public, and I wouldn't, either. But the 1978 Gibson RD Artist, that's another story.