Ok man, they can always attacth the sword in the body pretty easy to fix the hands solution, you have a point on the Sparda choosing its own wielder tho.
LOL I imagined Griffon stabbed with the sword trying to fight.
But seriously, how do we know if that is even going to work? It's a big ass assumption hence why V only had Nero as a last resort.
Griffon: "Can he win and change your fate?"
V "I can't say, but i'm don't have a choice but to share my fate with him"
He literally can't say what is gonna happens if Nero and Urizen crashs with eacth other, the same guy who knows the power of everybody and how they compare with another demon with absolute easy, can't tell if Nero will win or lose against the strongest Demon King in existence, do i'm need to say anything more about how strong Nero is after his training? Sure, later, Urizen got stronger as Griffon points out, but still don't take away how powerfull Nero became after his training.
I think you are forgetting some very important stuff. When V first met Nero he was unconscious and in a hospital, waaaay weaker than he was even during DMC 4.
Now there was a whole month in which Nero was training and he got the devil breakers, from the Nico report we know for a fact that he is at least as strong as he was during DMC 4.
When V meets him again is when Nero has regained all that power back.
Whether V sensed his power or not is irrelevant, whatever power Nero has is irrelevant because Nero is all that is left for them.
V doesn't say "Nero has a better chance than Dante" or something along those lines, he just goes "He can win? Idk but I really hope so"
That doesn't put him in any way, shape or form relative to Dante or Urizen.
The story even confirms this when V goes looking for the Sparda in hopes of getting Nero more power. V knows that Nero is far from whatever victory they need but that's all they have, they can't afford anything else.
That's why when they find Dante V is relieved because they now stand a chance.
In short: V had bronze (Nero) went looking for gold and found Dante.