Each Zealot wore an injection harness that delivered a continual flow of Imulsion into their bodies, amplifying the power of their attacks and granting them increased resilience and strength.
Like their unpowered brethren, these Kantuses heal and buff surrounding Locusts with the added durability enhancements and toxic explosion upon death. As such, they should be the first to be targeted and eliminated as a combined Zealot and Disciple duo is a dangerous combination indeed.
Like the Disciple, it is unknown why Ukkon decided to inject Imulsion into the Locust, given the fact that the threat of Lambency was widely known amongst the Horde by the time Gears Tactics took place. Injecting these Locusts with a mutagenic organism that infects the host against their own kind, seems counterproductive to the Locust Horde.
It's possible Ukkon was attempting to replicate or even enhance his own unique ability into the Locust's forces, using Imulsion.