Capture critical:(a form of Twice Critical that isn't Dragonic in nature, and requires the capture of a super natural being inside the gear and gives abilitys of the being to the user with out the species natural weaknesses, ex. Capture a fallen angel and gain the ability for wings and light spear, with out the weakness to demonic magic, all with the boost. Capture up to three beings at best.)
-inspiraction, Burst Hearts from Pokemon ReBurst manga

The Kinship Stone: a unique sacred gear similar to Blade blacksmith and Sword birth in the nature that there are multiple, but it hold a power far different. One can form bonds with animals, big or small, natural or super natural, weak or powerful, and manifest get power through that bond.
-inspiration, Monster hunter stories.

Soul Sabre: a sword sacred gear, but unlike Blade Blacksmith or sword birth, it generates a sword that reflects the holder, the sword itself can develope a specific ability reflecting the holder and act as a conduit for magic casting.
-inspiration, keyblade, I based the idea of keyblades, but removed the key part that allows the lock magic, and the connection to hearts of others, tho that could be a balance breaker or possible subspecies ability.

Diabolic Genesis: a sacred gear that God made at the same time as Boosted gear and Divine Dividing, Lilith was captured and sealed inside, however, in doing so restored her mind, as she has forced her mind to destroy itself after suffering from her curse, and being used as a breeding machine to produce the devil race. Diabolic Genesis allows the user to use Lilith as a Incubator for demonic creatures, that are bound and controlled by the Sacred gear and the user, the user can also program strengths and weaknesses in the creatures, they can be sentient, mindless, or even feral if the user chooses. It is not limited to humans, but anything the user get get their hands on. This Gear is immoral in most cases to use, making Lilith give birth and use said children as weapons in combat. This is an abstract and powerful Gear. It should be noted that Lilith wasn't labeled the Sin of Lust because she was lustful, it was because her body and figure attracted lust, and stayed a symbol of it no matter how many children were born from her hips.

This is less an idea and more a possibility. Blade Blacksmith and Sword Birth aren't actually limited to swords, it's the locked in default so the user and defend themselves, they are fully capable and making other weapons and tools from the sacred gear, such as armor, shields, maces, etc. Also, they can merge existing swords they made to make a higher quality blade, as well as use existing materials to forge different type of blades.