I... really, really hate to be this negative, after you've obviously put so much work into this, but... what you are doing here is basically starting with wild speculations that you drew from thin air, presuming they are entirely correct, then drawing more wild speculations out of thin air that don't follow logically from anything previously established but are purely something you made up, presuming those are entirely correct as well, then repeating the last few steps multiple times. In other words, as far as I can tell, your method is as unscientific as it could possibly be, and there is no proof that Erfworld works even remotely the way you describe it does. I'm genuinely sorry to be this harsh, but that's how I see it.
Some examples to illustrate why I think that way (prefacing every single statement of mine below with "as far as I remember, given the information we've been given so far,...").
Or +14, or +700, or +50%, or +7d6. We have not been given any information on the numbers involved, nor in what way it bolsters the units precisely (you assume it increases their Attack and Defence ratings, which may or may not be true), nor whether the increase is additive or multiplicative.
You literally pulled that out of a hat. To the best of my knowledge, we don't even have any indication that warlord units get any kind of attack or defence bonuses (they would be stronger just on account of coming with a leadership bonus anyway), nevermind a specific number for that.
Firstly, every number for the infantry, as well as their specials (like pikers being better against stabbers specifically) comes entirely out of nowhere. Secondly, there is no indication that even and odd levels have different effects. Thirdly, levels may or may not have fixed effects; it's equally possible for them to be randomized.
There is no reason to assume archer promotion is any different from stabber or piker promotion. Knights being stronger in combat than warlords comes from nowhere, and there is nothing indicating knight- and warlord-status are mutually exclusive.
Just look at what goes into this conclusion for a perfect demonstration of what I'm talking about. You're basing this off basic infantry having roughly 1/1 stats - which you made up - warlords having a +3/+3 bonus - which you made up - and knights being stronger than warlords - which you also made up!
It just goes on and on. We don't know what kind of dice are rolled in combat, we don't know with what frequency units attack, whether they do so simultaneously or whether there is some sort of initiative system, we don't know if units have a limit on the number of attacks they do in a turn, we don't know how the various stats interact (is Defence like Armor Class in D&D, making you more difficult to hit, or is it damage reduction - which you postulate to be a property of heavier units instead?), we don't know whether damage is fixed or randomized.
I realize you are merely speculating, and speculations are fun... but if they are not founded on actual information, and instead rely on stuff entirely made up, they quickly become pointless, as they lose all touch with reality and drift off into the realm of pure imagination. And I fear what you have done isn't so much moving past that point, as blazing past it with warp engines going full overdrive.
I really don't want to bring you down, and I hope my tone doesn't come across as too mean - because I really, really don't mean it that way - but, I think if you want to speculate about how Erfworld works, you'd be better off sticking more closely to what we know (which, I admit, is probably too little for any proper conclusions), and making up less stuff as you go.