Jay,
There are two types of cleavers. Bone cleavers are extremely heavy and will easily chop through chicken bone,crab shell, and other bones like veal and lamb. I have never seen a bone cleaver damaged by any type of bone.
Vegetable cleavers are just that...lighter knives which are shaped like cleavers and intended only to cut vegetables and to do other light work like chopping herbs. I have seen major damage inflicted to this type of knife over the years when used do perform the wrong task.
Get yourself a heavy *ss Dexter Russell bone cleaver made in good ol' Massachussetts
http//:www.dexter-russell.com/