Can't prove it, as it was never stated. But the facts all point to the same answer.
We had Wolverine.
Peak human yada yada.
We had Death.
Super strength
Super speed
Super durability far above what his norm was.
What's the difference between the two? One wears a suit, given to him by a guy who does nothing but upgrades mutants, especially when he makes them his horsemen. What was Wolverine? A Horseman.
All signs point to the suit.