Armor skill

[nacional100]

Hi, noob here.
What are the exact benefits of training armor, apart from reducing EV penalty?
Also, I read somewhere that I shouldn't train armor while wearing a robe. Why is that? Does the training add more AC when I am wearing a heavier armor?

Thanks

[goodcoolguy]

It reduces penalties to EV and spellcasting, but not stealth, due to heavy armor. It also increases the amount of ac you get from armor, including auxiliary armor, but not including pluses from enchantment or non-armor equipment, by a certain factor that scales linearly with armor skill. I think the details given in the wiki on this topic are basically correct.

[Sprucery]

Add together the base AC values of all your pieces of armour (e.g. ring mail 5, helmet 1 etc.). Now every level of Armour skill increases your AC value by [total base AC]/22.

So if you are only wearing a robe, you will get one point of AC at 11 Armour, which is not very efficient training. But if you have a robe, helmet, cloak, gloves and boots, every 11/3 Armour will give you extra AC. Early skill levels are cheap so definitely train for one extra AC in this case (at some point).

[nacional100]

Add together the base AC values of all your pieces of armour (e.g. ring mail 5, helmet 1 etc.). Now every level of Armour skill increases your AC value by [total base AC]/22.

So if you are only wearing a robe, you will get one point of AC at 11 Armour, which is not very efficient training. But if you have a robe, helmet, cloak, gloves and boots, every 11/3 Armour will give you extra AC. Early skill levels are cheap so definitely train for one extra AC in this case (at some point).

So I shouldn't train until I find some heavy armor?

[Sprucery]

So I shouldn't train until I find some heavy armor?

If you want a simple answer, yes. You generally want to train the skill that gives you the most benefit at the moment. But when you have your aux armour slots filled, training some Armour with lighter body armour starts to be reasonable.

If you want more specific advice, post a character dump.

[Midn8]

From the learnDB for AEVP:

Adjusted body armour evasion penalty. Affects spell success, melee and missile accuracy. Its value is [(2/5) * er^2 / (str+3)] * [45 - armour_skill]/45.

So armour skill helps you with heavy armour. No surprise there. However, discounting magic enchantments, An armour skill of X adds X/22 armour, so if you have a ton of armour, more skill helps a lot.

[nacional100]

But if I train armour while wearing light armour and then I start wearing heavy armour, the bonus is the same than if I had trained while wearing the heavy armour, isn't it?
That is what I am not getting. I won't be wasting skill points, even if my training is not immediately efficient.

[Sar]

If your training isn't immediately efficient, you probably are wasting your skill points.

[VeryAngryFelid]

I guess different players have different meaning for "wasted".
"I won't train Armour as Sp in robe because it gives me 0 AC until skill level N"
"I won't train Polearms to 26 because my current Glaive at min delay is good enough".
"I won't train Polearms to 26 because my current Demon Whip at min delay is good enough"
...
"I won't train Poison Magic on D1 as VM because I won't use Poison spells for my last rune in Tomb anyway"

[TwoLeggedMammal]

But if I train armour while wearing light armour and then I start wearing heavy armour, the bonus is the same than if I had trained while wearing the heavy armour, isn't it?
That is what I am not getting. I won't be wasting skill points, even if my training is not immediately efficient.

The danger of making long-term plans in Crawl is that you'll neglect something you need right away in order to train something you may eventually want; that could get you killed and then indeed it does become a waste.

But even if you survive just fine, you could always find an amazing randart robe or mottled dragon armor that you don't ever want to take off. At the same time, there are other skills which you are certain you'll use the entire game which could use the XP. If/when you do come across good heavy armor, it won't take long to get the skill to a respectable level.

[ximxim]

But if I train armour while wearing light armour and then I start wearing heavy armour, the bonus is the same than if I had trained while wearing the heavy armour, isn't it?
That is what I am not getting. I won't be wasting skill points, even if my training is not immediately efficient.

It might be worth doing this early game if you know you're going to switch to heavy armour (and some is very likely to spawn in the first few floors), mainly due to how accuracy and evasion works. In most reasonable cases this won't give you more than 1-2 points of accuracy on average (depending on how rounding works, not sure), but in the early game you are basically starved for accuracy, so this can amount to something like a 15+% increase in average damage.

[VeryAngryFelid]

For accuracy it is better to train Fighting than Armour, at least early.

"Fighting gives you a bonus of +0 to +Fighting." http://crawl.chaosforge.org/To-hit#Base_Value

Also Fighting gives you more HP and Damage unlike Armour skill.

[ximxim]

For accuracy it is better to train Fighting than Armour, at least early.

"Fighting gives you a bonus of +0 to +Fighting." http://crawl.chaosforge.org/To-hit#Base_Value

Also Fighting gives you more HP and Damage unlike Armour skill.

More or less, see also https://loom.shalott.org/learndb.html#to_hit. Fair point though, fighting is more valuable in most cases.