Help translating this phrase..

Latin Learning Latin
1

I was reading on Gabriel Vásquez, a Spanish Jesuit theologian of the 16th century (in case anyone wants to know), and he was referred to as the following by some other guy who doesn’t seem all too important:

vir fuit acerrimo ingenio

My best translation of that would be:

The man (who) was with the keenest intellect.

But that doesn’t seem entirely correct to me. It seems a little off.
So what would be the correct, or a better translation?
And besides that, what use is that ablative in? My best guess would be ablative of manner, but I’m certain I’m wrong. I don’t know too many uses of the ablative at the top of my mind (currently working on that though).

2

Maybe it’s more idiomatic to translate it as

he was a man of keenest intellect.

3

Awesome. That sounds so much better. And what use of the ablative is acerrimo ingenio in? Would you know?

4

Quality?

5

Don’t remember ever reading of that one. I look into it in Gildersleeve’s grammar.

Thanks.