It's honestly a plague I've been finding more and more common with not just this, but just the overall conflating of everything with everything else. The whole idea behind "prayer warrior" is to try and create some sort of equality between the words, or to diminish the meaning of words. Same with how they label people and things all the time as terrorists or acts of treason. It's as if the shock value of the word is what matters over the meaning but over time it gets the cried wolf syndrome so now we have an entire political party in America unironically calling themselves domestic terrorists.
I've heard prayer warrior since I was a kid in the 80s. The idea is that the prayer warrior is fighting a spiritual battle instead of a physical one. How is it a battle? Well when they start praying, Satan will start to attack with doubts and fears. So it's a fight to preserve and continue praying.
All garbage as far as I'm concerned, but to them is has nothing to do with changing the meaning of words. It's the best way they have to describe how hard it is to pray for hours on end for multiple days when you have a brain telling you that this is silly.