Armorer
Characters who grew up as an apprentice under, assistant to, or who practiced the works of a blacksmith and armorer, will have the chance to have this particular Extra Skill. For it pertains primarily to the knowledge of armors & how they are constructed, including the forging process, shaping process, binding process & fitting process. Thus while the character never has to be the one making the armor, they do need to have been exposed to the process for long periods of time. This time would need to be vastly longer if the character is learning on their own without a mentor.
With the knowledge and experience of an Armorer under their belt, characters with this skill can expertly appraise armor without any rolls, & properly determine the condition of the armor. This could result in discovering that the armor is flawed in some way, and thus subjected to breaking in the middle of combat, an average but good quality armor, superior armor made with expertise that can take more hits than most other armors, or even whether the armor is on the verge of falling apart or is in peak condition. In addition, should one with this skill spot any damage to the armor, so long as it isn't irreversable, they can repair the damage with the appropriate tools, materials and time to do so without any rolls (unless rushing the job).
Furthermore the character with this skill can attempt to spot weak points in their enemy's armor. To do this, they must roll an Armorer Proficiency Check (no attribute modifiers allowed for this), with a +4/20% penalty to the roll in the middle of combat. Should they succeed their check, any attack made by the skill owner against the target's armor which deals half or greater damage makes the armor save vs. crushing blow with a cumulative -1 every attack against it. The armor will automatically break if the skill owner lands a natural 20 against it. If the armorer relays this knowledge to their allies, the non-skilled combatants landing a hit cause a saving throw but with a +2 to it's modifier. Depending on the armor, damaging/breaking it will bring the AC to 10, or simply lower it's armor class by 4 grades.
With the knowledge and experience of an Armorer under their belt, characters with this skill can expertly appraise armor without any rolls, & properly determine the condition of the armor. This could result in discovering that the armor is flawed in some way, and thus subjected to breaking in the middle of combat, an average but good quality armor, superior armor made with expertise that can take more hits than most other armors, or even whether the armor is on the verge of falling apart or is in peak condition. In addition, should one with this skill spot any damage to the armor, so long as it isn't irreversable, they can repair the damage with the appropriate tools, materials and time to do so without any rolls (unless rushing the job).
Furthermore the character with this skill can attempt to spot weak points in their enemy's armor. To do this, they must roll an Armorer Proficiency Check (no attribute modifiers allowed for this), with a +4/20% penalty to the roll in the middle of combat. Should they succeed their check, any attack made by the skill owner against the target's armor which deals half or greater damage makes the armor save vs. crushing blow with a cumulative -1 every attack against it. The armor will automatically break if the skill owner lands a natural 20 against it. If the armorer relays this knowledge to their allies, the non-skilled combatants landing a hit cause a saving throw but with a +2 to it's modifier. Depending on the armor, damaging/breaking it will bring the AC to 10, or simply lower it's armor class by 4 grades.