I vote for either throwing blades (It'd be really cool if they had some kind of javelin type weapon, with a rope so they could hit figures and pull them in. But I doubt that can be programmed in).
Bolos with a stun mechanic (they release a tiny dust cloud upon impact)
I'm a huge fan of the bolas. They already use throw and whip skill so great for ghouls. They are among my personal favorite weapons. Good at both range and melee. Not excellent, but good enough. I don't think they need to release dust clouds. My dwarven bola squads usually stop gobbos (and especially warlocks) dead in their tracks with bolas. They chip bones frequently. (And if made out of high quality materials, dismember unarmored bits like hands and feet.
Bolas should definitely be an option to craft. Although, back on the dust cloud thing...cool enchantments for bolas are a plus :p
But warlock bolas could definitely be a great deal more...twisted. Good races, use them for hunting, or for defense. Warlocks use ghouls that scour the land for more...parts. What would a bola used by ghoul look like? It might not even be built, but grown. Unnatural twisted strands of nether creeper with thorn barbs, dripping in poison that increases pain and causes bloody wounds that remain open, gaping, and oozing blood.
It's not enough to just gather resources. For the warlocks, they need to know those resources died screaming.