Hi Fernando,
I'm happy calling it a "sickle" (arit), but I'm not sure that being heavier means it's primarily a weapon. There are major variations in the weights of farm tools, with heavier ones being used for heavier work (for instance grass cutting vs. vine cutting vs. brush cutting vs. wood cutting). An example of this is seen in
The Wikipedia article on billhooks, not that I think you have a billhook exactly.
Just to give you a comparison, all of my kukris weigh more than your arit, and they're all designed for wood cutting.
F