Dlanor's red key negated the concepts of evasion, resistance, stamina, and defense. What makes you think Bernkastel can't?
Since when does the Red Key negate stamina?
The Red Key - A weapon for emergencies used by official Inquisitors of Heresy belonging to Eiserne Jungfrau. Dlanor's primary weapon. Unlike a normal weapon, whose purpose is to cause physical damage, this special tool is known as a conceptual weapon, and it is used to deny the existence of concepts.
Regardless of whether the target is physical, mental or conceptual, it is impossible to use any defensive concept, such as physical barriers, mental isolation, and conceptual inheritance, to defend against this weapon. Because the concepts themselves are denied, even the concept of resisting an attack does not exist, and it is impossible for the target to endure regardless of their stamina. Furthermore, all supernatural methods of buying time, such as teleportation, time reversal, revivals, and inheritance are impossible. Because denials of concepts conform to verdict procedures dictated by the Great Court, all future concepts that disobey them will be denied immediately. In addition, when the Red Key forms a complete Barrier, all concepts of evasion cannot be successful.
Defense is Impossible, evasion is impossible, buying time is impossible. The ultimate conceptual weapon is the embodiment of these three impossibilities.
The weapon's purpose negates all probable defensive measures that could be surmised in reaction to the weapon's attack, not negating any connection a being has to any sort of existential concept if they are an abstract being, high-level reality warper or omnipotent/ nigh-omnipotent being. I've argued this before when mention of the weapon's properties was trying to be applied to another abstract being.
When were Galactus heralds multiversal capable of making more multiversals?
I only said that the means that the role that Bernkastel was made from Featherine is of a similar one to Galactus with Silver Surfer and his Heralds. Is she more powerful than the Heralds? More ridiculously so. Does this make her an abstract? Unless she represents some sort of existential concept or phenomena, I'd have to say this idea is nothing but hot air.