I think either colour choice would work. I'm not experienced or confident enough to try serious painting without Sorastro. However if I was forced to I'd probably paint the gloves with the following:
Mournfang Brown -> Agarax Earthshade -> Mournfang Brown -> Skraag Brown
I compared the color to Diala's cloak and after a little more self-debate I ended up going with just pure Mournfang brown. Here's how Biv looks with just most of the base colors and some highlight tests on the skin:
Also, thanks for the highlighting tip.