Definitive explanation for armor upgrades in EBII?

[Shoebopp]

I've researched this topic a lot and there seems to be 4 schools of thought on how armor upgrades work in M2TW and by extension EBII

1. Each upgrade adds 2.5 armor (EBII "official" answer)
2. Each level adds an individual bonus between 1 and 4 depending on the level
3. Each level adds a cumulative bonus of all levels' bonuses all the way up to that level
4. Each level sets the armor to the cumulative amount

#2-4 were theorized by players in 2007, while #1 was answered by a player in 2017, so I'm inclined to believe the more up-to-date answer. But for anyone with advanced knowledge of M2TW internals, which explanation is correct?

[eyelurker]

Probably 1 but only because i believe EB2 team has tweak the armor upgrade

In mtw2 vanilla upgrade armor always shown in screen to improve 1 armor yet the first armor upgrade which is padded armor have value of 4 which can be seen in unit like italian spear militia

[Shoebopp]

Here's more sources supporting theory #1 after an embarrassing amount of research:

https://www.reddit.com/r/totalwar/co...rmor_upgrades/
https://www.twcenter.net/forums/show...grades-trigger
http://www.twcenter.net/forums/showt...rms&styleid=40

Looks like the EBII team never tweaked the values. It's just that the whole armor system was misunderstood for quite some time. The most recent theory is that each upgrade increases armor by 2.5. Kinda reminds me of how casualty recover was thought to be influenced by means of death (arrow, javelin, melee, or cavalry charge), rather than order of death (first 30% vs latter 70%) as it actually is.

[Shoebopp]

Fun fact: if theory #2 is true, then based on this theorized upgrade table

Lvl 0 = Flesh, 0 defense
Lvl 1 = Leather/Padded, 4 defense
Lvl 2 = Light Mail/Chain, 6 defense
Lvl 3 = Heavy Mail/Breastplate, 7 defense
Lvl 4 = Partial Plate, 8 defense
Lvl 5 = Full Plate, 10 defense
Lvl 6 = Advanced Plate, 11 defense


Gallic Nobles will have an armor rating of 18 by the Celtic Twilight Reforms (reform #6).

If theory #3 is true, then Gallic Nobles will have an armor rating of 46.

Only theories #1 (armor of 12) and #4 (11) provide sensible values. However, if theory #4 is true, then Thracian Colonists, who initially have an armor of 6, will get sidegraded to... 6 after the Thorakitai Reforms (reform #2). Fingers crossed that theory #1 is the right one.

[Tactics Mayers]

Kinda related but does unit experience also have the same problem as armor upgrades regarding inaccurate displayed stats vs actual effects and hidden bonuses?

[Shoebopp]

Kinda related but does unit experience also have the same problem as armor upgrades regarding inaccurate displayed stats vs actual effects and hidden bonuses?

Google says no. The only "hidden" bonus is the +1 morale each chevron gives. You can't see morale bonuses, so maybe that counts.