I thought we already had a thread on this, but I can't find it.
I found the following blog post that was pretty good, save I felt, as one person commented, the writer mistook the term Masterwork for Masterpiece.
https://lootthebody.wordpress....s-in-5th-edition-dd/
I don't know that I even considered masterwork armor before seriously when I had thought about things originally. The idea of re-rolling when the opponent gets max damage on a die was really interesting, and something was I don't believe I had even considered.
As I thought about it, even though it really on average should only amount to reducing damage by 1, it seems potentially a little powerful. Some thoughts however include, simply reducing max damage by one, or maybe even reducing minimum damage by one. [perhaps even allowing it to be reduced to 0] Other options might be to limit an ability to only affecting a type of damage [piercing, bludgeoning, slashing, etc] Given how 5th edition gives more value to AC and armor, restricting this ability more than perhaps how weapons are might make some sense.
One of my concerns, if we presume that traditionally, magical items start out as masterwork items, I don't want to greatly inflate the abilities of +1 items by having an additional effects.
Actually, perhaps I should suggest that I'm not against allowing masterwork, at the level that would behave like a full +1 to Armor or Weapon is probably fine but the bonuses wouldn't specifically stack. Technically, also full non-magical +1 items, I believe will cost more than magical +1 items, as the skill to create them will be less common than the average wizard whom can enchant a basic +1 item based off a common masterwork.
Weapon Masterwork options
common:
+1 damage to minimum damage, or max damage
uncommon:
re-roll minimum damage
rare:
full non-magical +1 [probably a masterpiece]
[vicious] may re-roll one damage die on a critical hit (and potentially sneak attack)
unknown rarity:
[unusual]Add an additional type of damage done with weapon
[big]
If light of finesse, +1 damage (loses light and/or finesse property)
If none of light/versatile/heavy, +2 damage (becomes heavy)
If versatile (not light), +1 one-handed damage; +2 two-handed damage (doesn't become heavy)
If heavy +2 (gains two handed, loses versatile if present but starts at versatile damage)
All that might be too complicated
Armor Masterwork options
common:
+1 AC vs 1 type of attack (piercing, bludgeoning, slashing)
uncommon:
-1 damage to one of (minimum/maximum) damage of one type of attack (p, s, b)
rare:
full non-magical +1
re-roll of max damage of one type of attack (p, s, b).
convert minimum damage of one type of attack (p, s, b) to a miss.
unknown rarity:
make light armor not be disadvantaged at stealth
increase max dex bonus by 1 of medium armor
Masterwork items are allowed their own save even if not carried by someone. (they may use their own save, or the individual carrying them, whichever is better)
Masterwork items should be granted at least one more HP, normally at least +10%.
Some other general choices might be simply:
tougher: granting more HP/toughness
lighter: reducing weight
A common masterwork above doesn't mean it is a common item, I'm just trying to get a quick categorization together. It may make sense to re-categorize them later to indicate the more common categorization.
Retrospective: although having a plus to AC but only against certain types of attacks would complicate some aspects of combat. If a GM is used to letting players know their target number, then you either review the presence of something special, or have to fudge the number up or down a bit and adjust if they hit. [players thinking they missed, when they hit, or thinking they hit when they didn't] The same could be true if you publish HP, although I think that would be easier to fudge, as forms of resistance and such affect damage taken. Just things to consider.