Turns out that most of the frame-rate bottleneck wasn't even anything graphics-related. It was checking for screen width and height on Android on every mesh draw which is much slower than checking GLSurfaceView dimensions for aspect ratio. Vertex lighting by expanding from room center until you hit walls works well, but produces glitches, especially where voxel chunks meet. The new higher frame-rate makes the fireballs fly faster, which makes the game harder. But it now runs smoothly even on my $100 ZTE phone.
What is next for Fateless? More weapons, more monsters, more levels.