
To make sure it doesn't mix with my Cursed Rune, I changed the color of the Cursed Rune to a deep purple. Given that the rune itself would be used as a way to make weapons cursed if you so decide it (I know you're on the fence about that particular rune), I figured the color change needed to be done in order to make the anvil-shaped hardening stone look more like wrought iron.
Before you ask, yes, I made the Stage 3 Hardening Stone look like a diamond anvil. Try and follow my example here; I make this stuff for a reason.
As for the stone itself, well, the idea was the Hardening Stone would provide a 10% defense boost to a single piece of armor. This would be not all that great as a 10% boost from a Sharpening Stone would provide close to its intended value: 10% damage (weapons have more of an effect on damage than armor). Hardening Stones? Let's say you have a full equipment set that's worth 40 defense for each piece (meaning the shoes would have 20 defense given the rule of thumb). This would lead to the following math:
40+40+40+20=140
If I were to harden a regular piece of armor, this is the equipment defense I would get from that:
44+40+40+20=144
If I were to go for the shoes, however, this is what I would get:
40+40+40+22=142
From that, if I were to harden a piece of armor, I would get the following defense boost:
144/140=1.02857
Just 2.857% What about the shoes? Well, it's even worse.:
142/140=1.01429
The defense boost you get from hardening shoes is a measly 1.429%.
Now, how do you balance it out, you ask? Well, there are three possible options to that.:
Option 1: Quadruple The Hardening Stones' Drop Rates
This option retains the hardness stones' relatively poor stat boosts, but it makes up for it by making the stones themselves 4x as common to fit their current buffs.
Option 2: Double the Defense Boosts Given
Having hardness stones increase defense in a single piece of equipment by 20% a pop instead of 10% would allow hardening stones to become more useful in the easiest way possible; however, this may require some power-balancing on the monsters' ends as the defense boost per stone would increase by a whole 9.091%. Not bad; it'll make hardening stones more worthwhile given we have to stick them into give different pieces of equipment with one stone per piece.
Option 3: Allowing Hardening Stones to Buff Every Stat in an Armor Piece:
This option is the most ideal out of all the options. Let's say you have a Lunatic Helmet. It has a Defense of 49 and a Strength of 18. Should I harden it one stage with this option in mind, the H1 Lunatic Helmet would have the following:
53 Defense; 19 Strength
An H2 Lunatic Helmet, on the other hand, would have stats like this:
58 Defense; 20 Strength
With that, it should be important to note that stats with 0 stat points should remain at 0. This means the Lunatic Helmet should gain no magic, archery, or artillery from this.
This would probably be the best way to buff the Hardening Stone; however, should it be implemented, I will have to revise the boss analysis sheets to adjust for not only the hardened equips, but also the accessories in the game since they'll be affected the most. I had to bold and underscore that to emphasize the importance of that task.
Out of all the options I've provided, Option 1 is the easiest, Option 2 is the least game-breaking, and Option 3 is the best option.
So yeah, there's that.