Same issue, but with the staff (I don't remember what I've picked from the pre-order item). Hope ANet fix this soon. The completionist in me is screaming :D
It is not only the Frostbitten Orichalcum Harvesting Sickle that is not working. I tried Volatile Harvesting Sickle and it does not work as well. Looks like all Harvesting tools have lost their power.