Fantasy Trilogy - Characters being chased by an Evil Darkness, looking for Good Light

[Paul Daniels]

SPOILERS AHEAD

- Published and read in the 1980s. Possibly first half of decade.
- The main characters are being chased by members of a religion/sect that have a hand cut off and replaced by knife or hook.
- Sect run by a number of high priests? who are bolted to chairs.
- Sect worships / controlled by a jar of darkness. At least its one of the plots.
- Characters searching for a girdle of light (possibly) that turns out to bind a number of pure beings/people that removes all evil. The evil ended up in the jar.
- One of the book covers is dark blue overall showing a hooded man who belongs to the sect showing the hook/knife.
- Part of the chase might be by ship.

Its been bugging me. I actually came across the Darwath Trilogy, which I'd forgotten about, while searching the net.

Thanks for looking.
Paul