It also earned Ms Grunwald an invitation to the World Combat Challenge in the United States in October.
"It hasn't really sunk in yet. For me it was just another challenge. I like a challenge," she said.
The combat challenge course involves a stair climb, hose hoist and stair descent, forcible entry, obstacle course and hose advance, and finishes with the victim rescue.
That's all done with firefighters fully kitted up, including in breathing apparatus in what is dubbed the toughest three minutes in sport.
Ms Grunwald said the experience in her first combat challenge last month helped her to the world-class time last weekend.
"I probably learned that every step counts. Because it's only a three-minute course I knew I couldn't really slow down anywhere," she said.
"It's a bit like in our job. You don't have time to think about it, you just do it and afterwards you deal with it. It's quite nice to see that the training or whatever you do, it's not just for the good looks, I can actually pull it off.
"I really hate failing. That's one of the big things in my life. I don't like coming second."
Ms Grunwald said she would be looking for sponsorship to get to the US for the World Combat Challenge where she would also receive her Lion's Den jacket and certificate.
Whanganui firefighters Daniel Townsend, Ian Tanner and Myles Hodder joined Ms Grunwald in the teams event.