In a book I found this sentence:
I understand the sentence, but I'm unsure about I should I read といえど; I found a bunch of answer on the topic of this ど (this, this and this), but two are about ども and I'm not sure about how to use the meanings given in the first in this case.
About 広し I found this answer, which explains it is a terminal form, so I think 世界広し means something like "The world is vast" (like 世界(は)広い).
Then on my grammar I found that も is optional, so といえど should be the same as といえども, an old form of といっても; so I think that part translates modern Japanese as 世界は広いといっても.
Initially I thought that the whole meant something like "Speaking about the vast world, the only one who could use it...", like といえど was equivalent to といえば, but after what I found about といえど and 広し and maybe that means something like "Even if the world is vast", "Even saying (about how much) the world is vast", like the world is big (and, implicitly, full of people), and yet only him can use the hammer?
Eiríkr Útlendi answer from the suggested question does help, but the confirmation that といえどもis equivalent to といえど, the notes on 世界広しといえど being used also in normal conversation, and the additional notes on the grammar of といえど(も) helped clarify better what the sentence means.