Making sense of the armor DR table

[PugPug]

http://pillarsofeternity.gamepedia.com/Armor#Base_Armor_Table

 

It looks like someone threw darts at a board to pick the resistances and vulnerabilities, but I'm going to try to see if there are any consistent rules we can keep in mind to choose weapons without consulting a spreadsheet during play.

 

Cloth and leathery things don't like acid

Brigandine is plates of metal affixed to leather with some leather exposed (the plates don't overlap like with scale), so like leather and hide, it is vulnerable to corrode.

 

Rigid metal armor is crushable

Scale, breastplate and plate have no additional resistance to crush damage.

 

...and that's it. That's all I've got. None of the rest of it makes any damn sense to me. Every time I think I see something that makes sense, I see an inconsistency with it somewhere else on the table.

[AndreaColombo]

Plate is weak against Shock. It makes sense because metal is highly conductive.

 

Sure, there are other armors made of metal in the game that aren't vulnerable to Shock ... but you know.