Balancing Eggshell Tops

Question

What Is An Eggshell Top?

Basically a seashell top, but with egg-shaped "shells" and the color and texture of ivory. This is an Enchanted item of clothing worn mostly by mermaids and Dancers; both prefer to wear less clothing, and this item enables that by granting 'durability like unto a Chomper' for the wearer.

By durability 'like unto a Chomper,' I mean an Eggshell Top enhances the wearer's durability to mimic that of a Chomper. Inside their enamel shell, Chompers are made of a thick jelly, almost as firm as rubber cement (dents when struck by a hammer but does not permanently malform), and so an Eggshell Top causes the wearer to get an increase in durability proportional to the difference in durability between a shelled an unshelled Chomper.

To be more specific, a Dancer wearing an Eggshell Top won't be pierced or bruised if someone attempts to stab her with a dagger, and will be unharmed by punches, falls (I'm not talking falls from cliffs and buildings, merely tripping or falling out an average-sized tree), kicks and so forth. Stabs and slashes will be ineffective, but bludgeoning weapons (maces, axes, warhammers, picks) can and will penetrate these enhanced defenses.

Cool Enchantment, bro! What's the problem?

The trouble is how the Enchantment works; it gives durability like a Chomper to the wearer, right? However, this provides an easy exploit for adventurers. Since, by definition, the wearer possesses the durability of a Chomper, and adventurers can increase their Fortitude (willpower, endurance, vitality, and durability) as they Level Up, this means the wearer can Level Up their enhanced fortitude and thereby achieve unnaturally high Fortitude.

This is bad because with Fortitude maxed, an adventurer is immune to conventional weapon attacks. In more precise terms, one needs high-end gear to harm an adventurer with max Fortitude, like an adamant sword or mithril mace.

Assuming an adventurer buys and equips an Eggshell Top at Level 1, and assuming both A) that one's base Fortitude is multiplied by 1.01 with each Level Up and B) a regular person's Fortitude at Level 1, wearing an Eggshell Top, is a nice 6 or 7 out of 10 (with 5 being average and 10 being the maximum possible limit), it becomes even more clear how bad this is:

Max Level: 500

Normal Person's Maximum Fortitude At Max Level: 725

Eggshell Top Wearer's MFaML: 870-1015

My question is simple: How Can Eggshell Tops Be Balanced?

I have an idea for a possible solution (placed below), but can't figure out how to make it work. I'm open to other ideas, however, and will appreciate all input.

Stagnant Shielding-Perhaps the degree to which Eggshell Tops increase one's durability A) never changes and B) is based off of one's base Fortitude and thus has a negligible effect as one Levels up? The trouble is, an Eggshell Top functions because its magic syncs with its owner's natural energies, which would logically make it increase one's increasing Fortitude, albeit by the same degree each time. I'm not sure how to explain this discrepancy, but this is the solution I'd prefer. Once again, I am open to other ideas.

Answer 1

The item gives the user the durability of a Chomper and NOT MORE. So assign resistance values to this "chomper resist" buff and make this enchantment set the users resistance up or down to this value. So you can have the resistances of a chomper but never more.

Answer 2

Now, I don't really get your explanation of stagnant shielding here(like, do you want it so that the more leveled up you are, the less effective the top is, or does it just slowly stop providing benefits as you level up, but don't lose the existing benefits(additive benefits? or something?)), and I happen to only have an explanation for the second, so that's what you're gonna get.

The eggshell top syncs with the energy of the user and amplifies it. An eggshell top has very, very little area/volume. Much, much less than a full-body covering. As such, despite being a (presumably) magic item(and as such able to contain and process more magic), it can only process so much energy. Think of it as a rubber band, pulled taut. At some point, the top reaches it's capacity. While you still can receive benefits by "stretching" the limits of the item as you gradually squeeze more and more energy in there, it becomes harder to squeeze more energy in as the top becomes more and more saturated with energy that it's processing. At some point, it reaches it's limit and stops being able to increase your durability by any significant amount. This can be applied to any magic item, really. Additionally, it provides an interesting mechanic: if someone has stretched the limit of their top for long enough, it could be stretched permanently, and would perhaps more easily process energy from high level users no matter who it is, which would be good for people who have already reached the limits of the initial item.

Edit: (I've misunderstood completely, so this explanation is complete nonsense. See edit below for one consistent with your explanation.)Thank you for clarifying. Assuming your level bonus is consistent(i.e +1 for level 1->2, +1 for level 134->135), I offer a much more ham-fisted solution. To prevent us from killing ourselves from exertion(or was it to prevent internal damage?), our body enforces biological limits to prevent our muscles from exerting themselves at 100%, which is why you see stories about people lifting up entire cars to save their children, but you don't see it while you're on the street. Similarly, the top requires energy to be used, nevermind that it doesn't(or does it? Your decision) actually consume the energy. The body of your humans enforce limits on the amount of energy you can "give out" to random magic items. This is measured as a percentage of energy, say, 2%, or 8% or whatever. When you begin gaining levels, you gain energy(capacity). Assuming(again), that this gain is strictly consistent, you would gain a consistent amount of Fortitude for each level. Again, this depends on gains through levels being consistent, no increasing returns or percentage gains.

Edit 2: Ham-fisted answer time! Oh boy! Your tops already have a rather low capacity. They are efficient, but their capacity for energy is a hard limit, rather than a soft one as proposed by the above explanations. This limit can easily be fulfilled even by the lowest potential level 1s(maybe over-exaggerating a bit, but you get the point). As such, even as you level up, your top will not gain more benefit(It occurs to me that I may have misunderstood you again, maybe check the directly above explanation).