Try not to pontificate about things of which you are completely ignorant. Not all Haka are war dances, in fact, the vast majority are not.
The jury is still out on whether
"Ka Mate" is a war dance (the translation suggests that it isn't), and
"Kapa O Pango" definitely is not.
The thing that is absent in both, which makes them not war dances, is any mention of maiming the enemy or wishing harm upon them. Both the All Blacks' Haka are about the challenge ahead, and most importantly, they require no audience. This is why the All backs were quite happy to do the Haka in the changing rooms in Wales in 2006 when the WRU tried to mess with tradition.
https://www.youtube.com/watch?v=B6rzmpQRZg4
Look how that turned out for Wales both on and off the field! (45-10?)
IMO, the All Blacks should only do the Haka on the playing field as of right in home matches. For away matches, they should offer it to the host union. If the host union declines, then they simply do it in the changing shed (which as we have seen, makes not a jot of difference to us) and the crowd is denied (the television audience will still see it). This shifts responsibility onto the host union, who then cop the backlash from their public (and they WILL cop plenty). I cannot think of a host union, other then perhaps the ARU, who would decline.
If you want a war cry, however, look no further than
La Marseillaise. Its if full of blood, gore, battle imagery and invocations of death to the enemy.
T
o arms citizens Form your battalions
March, march
Let impure blood
Water our furrows
Drive on sacred patriotism
Support our avenging arms
Liberty, cherished liberty
Join the struggle with your defenders
Under our flags, let victory
Hurry to your manly tone
So that in death your enemies
See your triumph and our glory!