Yeah. You'll know when they have divided because the daughter plant will have a root system. Just snip it off (the whole daughter plant) and plant the roots in your gravel/substrate and you have another sword. Cool!
Maybe your water conditions aren't ideal for dividing. I had 2 swords and one has divided so now I have three, but that was over a month ago. I keep checking daily to see if either of the more mature plants are about to divide, but nothing lately. Anyone have any recommendations are encouraging the division?