To me fear is,...
A natural warning system.
It alerts us to the possible dangers we can encounter.
However, it is my belief that wariors acknowledge thier fear, but continue with the task at hand.
If a warrior is crippled by his fear, all his training is useless.
Likewise during training fear, fear of appearing uneducated about performing an action, or fear of being ruddiculed could cripple the warrior form learning and grasping what is being taught.