Hey! I was initially determined to go with one set of axe/shield and one set of scythes. However, I've done a complete about turn.
In terms of axe/shield vs. swords, it was the difference in cost that swung it. Axes at three times as much is painful. I was a huge fan of the save from the shields, but figured the penalty to hit and fewer attacks couldn't be mitigated as easily as the save (e.g. by putting them in a Wave Serpent as you're doing!).
In terms of scythes vs. cannon, I will be building the models with scythes as they look much cooler to my eye. However, I'll be playing them with wraithcannon. (I play in a very liberal environment, will be painting up Witch Elves to count as Striking Scorpions, Kabalite Warriors as Fire Dragons, etc.). I can't bring myself to pay more points for the scythes when they're shorter range.