The arm device he wears allows him to modify his "slow", creating different effects on those within the field. One notable effect he could create was an "EMP" that shorted out technology and weakened parahuman powers.
↑ 1.01.1Final Hour was more muscular, with tech wrapped around one of his arms, ending in a blunt design that resembled a brass hairdryer, with red smoke pouring from the fans and vents along its length. Aside from the brass helmet he wore, which covered his entire head the armor covered only half of his body. [...] They all shook hands. Snag’s giant mechanical hand made for a peculiar image as it met Final Hour’s hair-dryer stub of a limb and the two shook. - Excerpt from Shade 4.3
↑Final Hour. The guy was big, had a bodybuilder physique, and his tinkertech was focused on one side of his body: both eyes, the left half of the face, one arm, and one leg. The tech was heaviest around his left hand, which was writ large by the gauntlet that encased it. A series of clocks and dials were set into the back of the gauntlet, a little satellite dish in the palm. [...]
Secondhand couldn’t help but feel that having that much weight on one side of his body would fuck up his back into oblivion. - Excerpt from Interlude 15.y II
↑“I’ll get to that momentarily. I’m doing these guys out of order. Final Hour, he has a targeted slow. One target at a time, if he’s aware of them, he can slow them, as an ongoing thing. He can swap it with a moment’s notice. Tinker gear applies other effects to slowed targets. Makes it so being slow also crushes you and makes it hard to breathe, or chills you. Makes it so he can target a friend and make it so they fall slow, and reduce the impact of their landings. He had a thing which screwed with-” [...] Where had I been? Final Hour, right. “He could attach an EMP thing to his slow that slightly hampered powers, made machinery grind to a halt. All through this oversized thing he wore that covered his arm and hand.”
“He’s wearing it now,” Sveta said.
“Okay, right, can’t see while I’ve got the phone to my ear. Foresight said they were using Final Hour to mask their business dealings. He was their heavy hitter and he might still be. I was thinking he might be using the EMP thing or something like it to keep people from looking in.”
↑“They use Final Hour to cover other business. Even if you avoid being caught in the sweeps, you won’t be able to look or listen in if they’re conducting meetings in banked timestreams.”” - Excerpt from Glare 3.6
↑“She says lots of mothers do, but they keep it to themselves,” the bearded man said. “We have time on our side in more than one way. He’s dying slowly, she says. Slowly.”