I'll catch you on the download!
It appears to be a long halberd with a shining blue energy blade at the top.
#124: Attack of the Centaurs
Nex uses his halberd against an army of Centaurs to help back up the Winx as they make protecting the panicking fair-goers their main priority. He blasts a Centaur away alongside Roy and his Sand Shield.
The Halberd is able to release powerful wind blasts that can knock a target several feet away.