Wagner took 14 wickets at 18.28 in the two Tests as he tormented the West Indies with his short deliveries angling into the body.
"No matter where in the world he bowls he can create some indecision. It's quite a unique skill. It's very hard to prepare for," Hesson said.
Wagner took nine wickets in New Zealand's innings win in the first Test at Wellington, including a career best seven for 39 in the West Indies first knock.
He bagged another five in the second Test at Hamilton, which wound up on day four on Tuesday with New Zealand winning by 240 runs.
Once new-ball pair Trent Boult and Tim Southee accounted for the top order on the final day of the second Test, Wagner worked over the middle.
In a 10-ball burst he took out Shai Hope and Shane Dowrich and ended Sunil Ambris' tour with a broken arm.
When Roston Chase tried to rebuild the innings and reached 64, Wagner came back to remove the stubborn batsman.
"He bowls a lot of balls between the chest and throat," Hesson said.
"A lot of guys can stand up and play it but if you stand up and play it and it bounces a little bit more you get drawn into playing a ball that perhaps you shouldn't.
"That's a skill that not many people around the world have. Some guys can do it for maybe a couple of overs ... For Neil, it's probably a more natural length than others and he can sustain it for 7-8-9-10 over spells."
New Zealand now move onto a series of limited overs matches and do not play another Test until England arrive in March.
First Published: December 13, 2017, 9:37 AM IST