In both their visiting and aiding of these mortals Zeus and Odin identified certain people that they considered great and offered them their assistance. If a god could come to a man and physically aid him, that would be an incentive to believe and worship. Both of these gods have a specific symbol of power. Zeus has his lighting bolt, and Odin has his spear. Both of these items have a somewhat negative interpretation.
Lighting is a destructive force and a spear is a weapon used to kill.
In our society, gods are usually displayed to have a very positive light surrounding them and a weapon may seem strange to us as a symbol of a god. We must also see that the gods both used their respective weapons by throwing them. It may be that the fear that they invoke will have people thinking that they can be punished, and if they are punished it will not be a simple slap on the wrist, but rather a spear or lightning bolt hurled at them. So I believe that this fear was used when the myths were being originally fashioned so that one would be intimidated to believe and worship. One last thing to be considered about these two gods, and their manliness, is that both of them were very fertile.