This probably belongs somewhere in the culture section, but ive no clue where
from a quick perusal, heres my conclusions.
uniquely compared to us, klingons developed without agriculture (the indigenous japanese nearly did, but got outpopulated by agricultural korean immigrants). This means Kronos is (or must have been) pretty rich in food (but we knew this anyway from the number of large carnivores).
So, iron age klingons were still hunter-gatherers (though more hunting than gathering it must be said). This means they wouldnt have had the concentrated populations to raise large regiments of men. A centralised government would be impossible or at least highly unstable as each community can easily become independant. Trade is a convenience but not a necessity.
All this means lots of skirmishers and lone individuals running around the battlefield, and probably not a whole lot of metal to go round (as this requires some centralisation to organise arming everyone).
Assuming that there are no large friendly beasts, then no cavalry, but maybe stuff like elephants (fanged carnivorous ones of course) ridden by brave klingons. Chariots might be present, but not popular as they would be hard to control (getting a free one way ticket into the heart of battle might be cool to some though).
Weapons wise, no bows or crossbows have been mentioned that i know of, but slingshots have (moy'bI'). Skirmishers would be armed with these and javelins (tlhevjaQ). Lack of archers really changes the battle field some, but i think they could be replaced with javelin throwers with chetvI' (the hook thing).
Spears were specifically made for battle (ghIntaq) and shields featured too (yoD), and they work best in ranks, so some sort of massed unit is suggested, though probably screened by their bravest warriors with axes ('obmaQ) to break up enemy formations (the vikings i think also followed this model).
Given the greater strength of klingons i think yoD could be quite massive making shield walls possible even without tons of drilling in it.
Given the hunter gatherer roots, im thinking some elite units would be ambushers. Stalking around the flanks and attacking when the enemy are already engaged with hunting spears, knives, etc.
Also of note are elite guard units which are the forerunners of the order of the batleth. They will be armed with weapons not unlike batleths and will probably be tasked with protecting the leader.
unlike other warbands who start up all whipped up and enthusiastic but quickly reconsider when they start to lose men, im thinking klingons would be reluctant to start with; challenging the leaders or each other, trash talking, etc. But once the fight gets going they will be out for blood; Heghlu'meH QaQ jajvam (it is a good day to die) indeed.
[Edit -- changed thread title]