The Bit of Wax comes from the Alters of the Dead during the hourly Dancing with the Dead event. The map announcements tell you where they will spawn and then you just have to get lucky and kill one. or more.
When you kill an Alter you either get an Offering of the Dead or a Bit of Wax .
You can also craft Moonlight Thread Skein from Strengthened Thread and Strange Acid.
Strengthened Thread you can buy from Tasartia at Alker Harbor and Strange Acid comes from Soldier Ants (Level 122) in Sahel Zone. There might be more mobs that drop it but that's all I know.
