How much nerf would Zoro receive if he used metal sticks instead of swords? Probably by 95%.
How much nerf would Law receive if he used a metal stick instead of a sword? Probably 5%.
Get the difference. Law uses his sword mainly for stalling and parrying. Outside of his room, he was stalled by Doffy's clone. Doing a small cut on a no name gifter was in fact the only sword related attack he did so far. Against Smoker? Just stalling. Against Doffy's clone? Just stalling. Blocking overheat. All things he could've done with a metal stick, literally.
While, with that same metal stick, he would have the full range of offensive moves from his room. Cutting everything within his room, removing hearts, ripping organs apart.
When people get this difference, maybe we can continue.
Uhm, yeah? He was stalling and being pushed back by Doffy. Until Trebol warned Doffy that he is within Law's room. And earlier, when DOffy was sitting on his throne, Law was stalled by a clone of Doffy.
Doesn't change the fact that it's his DF that does the job. SFX slice, what is this supposed to mean? Yeah, he slices his opponents, but it's done with his Ope fruit, not through his sword.
Brooks sword(smanship) is still his main combat power. His DF is supplementary. It's different with Law. As for Law, his swordsmanship is supplementary, while his DF is his main and by far strongest asset.