I tried activating Conjunction Voltage, Cascadia Flare and Primary Frostbite by using a Djinn equipped with Verglas. I noticed that whenever I am riding Merulina, the procs from Verglas do not count towards these arcanes. I also tried using Cryotra, but the issue still persisted. Normally sentinel weapons can activate these procs, even when a weapon with the arcane is unholstered.