Axes will crash the game if the model filepath is incorrect.
Go to the data directory for the mod and find the descr_projectile text document. Then do cntrl+f for quality_thrown_axe
The last two lines of the quality_thrown_axe entry contain the file paths for the axe model. The name should be something like this:
model mods/americas/data/models_missile/francisca_high.cas, 40 ; mods/theraV4/data/models_missile/francisca_high.cas, 40
model mods/americas/data/models_missile/francisca.cas, max
Note: Since I just renamed the mod as americas to use the steam launcher, the filepath is also changed from mods/theraV4 to mods/americas