There are some things that are already in the module, dropping from creatures, but don't really have any use. I think they should be made useful before adding more new body parts to use. These here for example just fill up the bag without purpose (except skeleton knuckles, but I've a suggestion for them):
5 skeleton knuckles -> diluted unholy essence -> lesser unholy varnish (1d4 negative energy on hit, 3d4 on throw)
1 vampire fang -> diluted unholy essence -> lesser unholy varnish (1d4 negative energy on hit, 3d4 on throw)
1 elite vampire heart -> concentrated unholy essence -> strong unholy varnish (1d8 negative energy on hit, 3d8 on throw)
1 cold stone -> diluted cold essence -> lesser icy varnish (already exists)
1 alhoon ichor -> strongest magical varnish(don't remember its name) -> strongest magical varnish (already exists)