Battlecraft demimateria has become the booby-prize of desynth, especially battlecraft I. Most of the recipes that require battlecraft are obsolete accessories. Fieldcraft demimateria is used for vanity items, that there is still currently a demand for (it also reflects in the market price). Perhaps a line of vanity weapons could be added? At least then there would be a use for these rocks.
Oh, and speaking of rocks perhaps some of the more useless jewels could be incorporated into new recipes as well. There are quite a bit of materials, of all levels and grades, that have very little use or demand (like peiste leather). It would be nice if the developers balanced out the use of various material, without defaulting to the same ones ever time (ie darksteel).