For peeps that find that when they try to combine this reciepe and get the message (cant combine in this container). There is two cestus molds on the NPC. One works while (of course) the other does not. Pale Golden Inlaid Cestus. In a reinforced Jewelry kit. (Golden Cestus Kit) Flask of Water Enchanter Bar of Gold Crucible Gnomish Heat Source Cestus Inset Mold
In a reinforced Jewelry Kit. (Pale Nihilite Cestus Kit) Flask of Water Pale Nihilite Cestus Inset Mold Crucible Cestus Inset Mold
In a Forge combine: Bar of Aligned Steel, Golden Cestus Kit, Pale Nihilite Kit and the (CORRECT) Cestus Mold.
For me it was the first Cestus Mold (about the 3rd row down on vendor window) The other one is about half way down ... the one I tried first .. =/.