Alm and Bruno felt the tension within the Eraser hammer's structure. They'd only recently built this weapon, using the best materials they could find. The power they wanted to channel through it was way beyond what they'd expected, but they thought it could handle it—yet here they were, surprised by its limits.
'Master,' Liumi's voice echoed urgently, 'this is happening because the hammer doesn't have a spirit to control it. Without a soul that's perfectly linked to its power, control will never be complete.'
Alm and Bruno sighed. The hammer was soul-less because the Law of Shadow Duality was embedded in it—a law only they could wield. But since they weren't truly connected to the weapon, using it was like trying to control someone else's body; they'd never achieve total control. (Chapter 750)
The hammer's material could hold up for what they needed, but just barely, and only if they managed to completely master its capacity.