I don't mean, "what button activates them," or anything like that. I'm trying to understand how shields function as a defense mechanism in The Legend of Zelda: Breath of the Wild. Here's what a (partially made up) version might be for how armor works:
Armor reduces the damage Link takes. Each piece of armor has a protection rating, and the pieces you equip (up to three) are summed up to generate the total protection. Each point reduces the damage taken by a quarter heart, with the caveat that any hit will cause at least a quarter heart of damage. (So, a four armor rating will reduce a three-heart hit to cause two hearts damage, and cause a one-heart hit to cause a quarter-heart damage.)
(Hat tip to @Fungo for helping me improve my example there.)
With a shield, I really don't know how it works:
- Does it repel some attacks, based on rating, and those it doesn't repel hurt the same? Or does it reduce the damage from all, and some are reduced so much that they cause none (and appear repelled).
- And how does it get used up by that mechanic? Is it worn down "once per use" like weapons mostly are? Or is a successful use "absorbing" some amount of damage, so it can be used many times agains a weak attack or once against stronger ones?
Best Answer
Firstly, a shield will block 100% of incoming damage. The shield may break, but you won't take damage if you're blocking.
This thread sums up a lot of how shields work quite well.
As for how damage is applied to the shield itself and how it affects durability, this page explains what does and doesn't hurt your shield. Essentially, blocking (but not perfect guarding -- this doesn't lower a shields' durability at all) and surfing on rough terrain are what lowers the durability of shields.
While not explicitly stated here, it looks like stronger attacks will eat up more durability, which would explain why guardian lasers are so devastating to shields.
As for how surfing affects your shield's durability: