You don't have to do anything since you're not the one she's angry at.

You start to lift your left hand as Asta moves forward, trying your best to summon up energy into it so you can defend yourself, but it turns out that such an action is unneeded as the female dwarf moves past you instead of charging at you. She moves past you to stand over Rolf's still bleeding form, standing at his feet as she looks over the length of his helpless ruined form. Rolf's eyes, already starting to lose focus, manage to move to her as he meets her gaze and a frown comes upon his face.

"S-stupid girl...what do...you think you're doing...with that? That is...my weapon..", he rasps out at her and she shakes her head fiercely.

"No! No, it is my father's weapon, as it has always been. You took it along with me and my mother because of the debt he owed you. You sent him off to the mines and you used my mother like a whore until she died. And then you made me your 'squire' when, really, you just treated me like your toy as well.", she seethed at him, her voice low but shaking with anger, "You treated me so badly...but I took it because to dishonor my family's name by trying to escape a fair debt was something worse than any of that."

You arch your brow at that, thinking that what she was describing was far worse than running away from a debt, but, then, you weren't a dwarf and couldn't understand their strange concepts of family honor. They took it to a degree that even a knight such as yourself couldn't fully understand. Even then, maybe you had never truly understood honor, if honor is what had led to your being betrayed, your sister's defilement and Asta's story of debt repaid through slavery and shame.

"I served you loyally and you said you would free me when we finished this mission. So I continued to serve loyally, even when I found out...what you were planning to do to a young knight who knows more about honor than any of the others, you...or even I could. So I went along with it out of my own fear and selfish need and, for that, I am ashamed. But, still, even after everything happened, I still served you loyally and took your degradation and ****. Because I believed you would honor your word and free me. I believed you still had some shred of honor like a true dwarf should.", Asta continues, her voice rising and her grip on the axe becoming tighter, "And how am I repaid for my belief? By almost being DECAPITATED BY THE MASTER I SERVED LOYALLY! You tried to KILL me! YOU BASTARD!"

With that, Asta raises the axe and brings it hurtling down towards Rolf. You think to stop her as you had wanted the dwarf to suffer and die slowly, but you don't move to do so. Let Asta have her ****. It sounded like she had suffered for far longer than you had at the hands of the dwarf on the ground, after all. You had had your ****. Let her have hers as well.

It seems, though, that Asta's plans of **** are not so simple as killing Rolf. No, she had something much more brutal in mind and you see that as the axe's glittering blade slices through the air...and then lands squarely upon his groin. There is a wet squelch of sound as tender flesh is torn asunder by dwarven mithril, blood spurting from the dwarf's crotch as Asta slams the axe down hard enough to stick into the ground below Rolf' body. Despite being smaller than the male dwarf, Asta still possessed the strength of her race. And that strength had been unleashed, along with her rage, upon Rolf's tender and delicate nethers.

The dwarf warrior gives out a strangle cry that seems to die out as he runs out of breath and, despite the hatred you held for the dwarf, you cannot help but wince in response as you feel your balls tighten up in sympathetic response. Rolf may have been a bastard, but you couldn't help but feel as though having his cock and balls cut by his own axe might have been more cruel than even you could have managed. Still, perhaps that was simply because, as an owner of a set of cock and balls yourself, you could only imagine how awful that would be if you were the one afflicted.

Rolf tries to speak but can only give out a pained squeak as Asta pulls the axe up out of the ground and from between Rolf's legs, the blood upon it seeming all the more grisly for its source. She pulls the axe up and then, for good measure, spits on the fallen dwarf warrior before finally turning to you. And, considering what had just happened, you find yourself moving to shield your groin with your left hand as your right still couldn't be moved freely.