MH5 is deadly in One Piece because most pirates and marines don't expect poison weapons. In Naruto that stuff is significantly more common and once Krieg puts the mask on Zabuza will know what is up and hide underwater. He could also just use a big water jutsu to blow it away if it proves too troublesome.
Really the question here is "could Zabuza hurt the super durable Krieg" because Zabuza is far more intelligent and sneaky. None of Krieg's weapons are gonna work on a guy who can safely hide behind smoke and clones, though Daisenso would wreck Zabuza if Krieg could land a hit. Push come to shove drowning him is always an option.
If Zabuza can trap him in a water prison, that'll be it.
Krieg's pretty tough for being a first-arc foe (he and Arlong are the only ones significant by later standards), I wouldn't expect it to be easy, but he's not used to fighting someone so sneaky.