「話すことができぬでも、頷くぐらいはできるだろう」
It's from a videogame, the story takes place in the past.
It means "You can't talk, but you can nod at least!", am I right?
I don't understand the way it's written. Why isn't it 話すことができぬが、? Or 話すことができぬ。でも、?
「話すことができぬでも、頷く(unazuku)ぐらいはできるだろう」
The first part of this sentence is archaic or old-fashioned. This is, of course, used in order to show the story takes place in the past. Let's rewrite the above sentence into a modern one.
「話すことができなくても、頷くぐらいはできるだろう」
It can roughly be translated into "You can't talk, but you can nod at least!", but it seems to me that the following will be better.
A similar Japanese sentence using 話すことができぬが can be constructed in this way.
「彼は話すことはできぬが、頷くことはできる」(He can't talk but he can nod.)
Comparing this with the above one, you will, I am sure, be able to understand the slight difference in meaning.