How to adequately use troops

[LusitanianWolf]

Why i am asking this? I'm playing a game right now with Koinon Hellenon VH/VH and my, until then dominating armies mainly consisting of good spearmen, awesome kretan archers and usually 2 cavalry units, are now getting butchered by the getai troops. I can't find any weakness in them. My archers are just able to take down some of their low armored troops, but their heavy armored and heavy equipped troops are so much better than mine.

Nope, they arent, is just that EB in VH battles is terribly unbalanced stat wise. There are some ppl who still do it but it requires a lot of micromanagement and in my humble opinion ruins the game (I like my battles to be chaotic and realistic). I've allways played in VH in vanilla or other mods but in EB I keep it at medium.

Anyway, what I suggest is that you pin the heavy troops and take care of the rest before coming back to finish them, a mass routing around them will drop their morale. Shooting stones in the back as it was said by Gugus is also a good idea. javelins usualy work very well too. And get their general. ASAP! But again, I dont play VH and havent played with KH for a long time.

Ok i'm now playing EB for some time, i've read some guides regarding troops but i still can't figure out totally the difference between different melee weapons. Yes i know weapons like axes have ap (whatever that stands for) which is good against armor, but what about the other weapons? Clubs? Swords? And especially spears. What are they good for? How should you not use them?

AP = Armour piercing, ignores half of enemy armour
Letallity = chances to inflict a letal wound when hits the enemy (in vanilla was 1, in EB is more like 0.1 or 0.225).

Clubs and axes: AP but medium letality, outnumber or flank enemy heavy troops with masses of cheap clubmen or axemen and they'll be finished.

Spears : Line troops, the mainstay of most armies. While most of the times not the best assault units they are usualy very versatile and can be used either as main line, flank guards (they eat cavalry for breakfast) and even as flankers (specialy if they trow javelins before charge).

Long Swords Hight letality. They slay your enemy fast so use them to break the enemy line. If they have large shields and/or armour they can also be good line troops.

Short Swords While some of them arent that special being just a nerfed version of the longsword ones, there are many that have AP being able to take easly more armoured foes and being excelent assault troops (ex: iberians, samnites). And others, while not having AP have very dense formations and good shields being good line troops and very versatile (ex romans).

Skirmishers: Multi task. Use them to distract the enemy, throw javelins at their back while theire engaged in battle, support other troops, and as arrow fooder. Most have to be carefull of cavalry but some have spears and can even make some light horsemen eat dust. The ones with dense formation and large shields or armour can also make decent line troops (ex: germans ones, indo-iranians, peltastai).....
Two Handed weapons Weapons of mass destruction or suicidal bombers. Keep them safe from missiles (as they will die like flies) and then quikly put them in the battle line, specialy in the flanks or rear.
etc, etc...
I could also talk about cavalry, chariots or elephants but I dont have all day and if you look around there are topics in the subject. And since you play on VH none of this matters because your elites are going to be eaten by outnumbered levy skirmishers in melee :P

What I also take very in attention is the size of the shields and formations:
Large Shield and dense formation: Main line
Small Shield or disperse formation: flankers and reserves