While farming in Meriphataud Mountains. I had this item equipped with blm subbed so I could use warp when I was done. As of this posting, I saw the description that says additional effect not latent effect. So tonight, I'm going to try them without blm subbed and see what happens. One thing is for sure, though. Lvl 34 Thf/ 17 Blm did work with this additional effect. I don't have all of my magic/combat skills info, but I'll post that later tonight when I try it again.
Well after doing several lvl 20 BCNMs with these, I can safely say that you do not need blm subbed for the effect to work. So far I get about 10 ice hits each time when doing the bcnm. I'm sure it's just a random hit with ice.