I'm making an OC for a High School DxD RP and I need ideas for Copy Gear's origin, lore, limitations, and Balance Breaker.

I want it to feel like it could actually exist in DxD, not just be a broken "copy everything and win" ability.

The basic idea

Copy Gear lets the user copy supernatural abilities they encounter.

That includes things like:

• Sacred Gear abilities
• Devil techniques
• Magic
• Holy/Fallen Angel techniques
• Senjutsu/Touki
• Other supernatural techniques

But it does not copy the person themselves.

So it cannot copy:

• Race
• Bloodline
• Genetics/biology
• Soul
• Memories
• Personality
• Combat experience
• Instincts
• The consciousness of an entity inside a Sacred Gear

For example, copying Boosted Gear would give the user the ability to use Boosted Gear's power, but it would NOT give them Ddraig, Ddraig's memories, or Issei's experience.

The 2× rule

A copied ability can have around 2× the potential/output of the original at an equivalent level.

But this does not mean:

The user's own body, Demonic Power, stamina, durability, and compatibility still limit how much power they can actually use.

Practice and stabilization

I decided I do want practice to matter, but not in the sense of learning every ability from zero.

The user already understands the basic function of a copied ability immediately.

The progression is:

Copy → Activate → Stabilize → Master

Practice is mainly about making the copied ability:

• Stable
• Efficient
• Safer to use
• Less draining
• More consistent
• Capable of reaching higher output

For very powerful or complicated abilities, the first copy might be unstable or only partially usable.

The OC has already trained extensively with Akeno, so this stabilization/control aspect is already part of the story.

What can actually be copied?

For example:

Rias — Power of Destruction: Yes, partially
Akeno — Lightning: Yes
Asia — Twilight Healing: Yes
Issei — Boosted Gear: Yes, partially
Kiba — Sword Birth: Yes
Koneko — Her Nekoshou biology: No. Her supernatural techniques such as Touki/Senjutsu: potentially yes
Freed — Holy/light techniques: Yes
Raynare — Light-based techniques: Yes
Sona — Water magic/barriers: Yes
Excalibur — Not the actual sword, but potentially some supernatural properties/techniques derived from it: very difficult and unstable

The hidden potential

I don't want Copy Gear to stop at copying.

Its deeper progression is:

Copy → Analyze → Combine → Create

The idea is that after enough experience, the Gear can begin understanding the underlying principles behind different abilities.

Eventually, it could combine aspects of different powers to create something completely new.

For example:

Lightning + Destruction

could eventually become a unique ability rather than simply using two attacks at the same time.

This would develop gradually.

Balance Breaker

This is the part I'm still unsure about.

I don't want the Balance Breaker to just be:

I'd rather it fundamentally change how the Gear works.

Something like:

Normal Copy Gear:
Copy → Activate → Stabilize → Master

Balance Breaker:
Copy → Analyze → Reconstruct → Combine → Create

Basically, the Balance Breaker would be the point where the user stops being just a "copycat" and starts being capable of creating original supernatural techniques.

Character context

The OC is a 17-year-old human who was reincarnated as Rias Gremory's Rook.

He's still young and inexperienced compared with ancient supernatural beings.

The Rook role gives him a stronger physical foundation, which is useful because his body needs to handle powerful copied abilities.

He has already been through several supernatural incidents and trained enough that Copy Gear is no longer completely new to him.

His long-term goal is to eventually become a Maou, so I want the Gear and its lore to have enough depth for a very long progression.

What I'm looking for

What would you make the origin and lore of Copy Gear?

Would you make it:

• An original Sacred Gear created by the Biblical God?
• A Sacred Gear specifically designed to let humanity adapt to supernatural threats?
• Something connected to an ancient user?
• Something that contains a spirit or consciousness?
• Something with a hidden purpose that even the current user doesn't know?

And most importantly:

What would you make its Balance Breaker?

I know the current version is already potentially overpowered. I'm not necessarily trying to nerf it into mediocrity; I'm looking for ways to give it meaningful limitations, lore, and progression so its power feels earned and believable within DxD.