To Be Used Of/For

Does "to be used OF" mean "to be used FOR":

wikipedia
The English term "empiric" derives from the Greek word ἐμπειρία, which is cognate with and translates to the Latin experientia, from which we derive the word "experience" and the related "experiment". The term was used of the Empiric school of ancient Greek medical practitioners, who rejected the doctrines of the (Dogmatic school), preferring to rely on the observation of "phenomena".

Or is it poor writing?

It's more than usual looking to me, since like many here I'm often looking into what words where used for, I'm also looking at what they were used of, and hence encounter the use quite often.

Of the great many cases in etymonline.com alone, a great many are exactly as used here.

Oxford have no qualms about using it:

The word was used of Irish peasants dispossessed by English settlers and living as robbers, and extended to other marauders especially in the Scottish Highlands. (Definition of Tory).

And nor do I.

To specifically address:

Does "to be used OF" mean "to be used FOR":

The phrasing specifically reflects the relationship between a word and what it represents. If you agree with the comments above that it seems like a forced attempt to sound erudite, then you could use for or perhaps about or "to refer to".

I for one don't, so while it's not a phrasing I often find myself using (even here, when what words were used of is a particularly common topic), I won't shy from it, either.

I wouldn't go so far as to say used of is always an indicator of "poor writing", but as this chart shows, it's very much a declining usage.

It's probably declined even more than the chart implies, since some of the more recent instances will be citing earlier texts. And if you compare US/UK usage in that link you'll see used of is at least twice as "unpopular" in the US (often a good indicator of where global usage is headed).

Obviously there's absolutely no issue of grammar involved here. It's essentially a stylistic choice, but arguably (assuming you're aware of the relative prevalences) if you do opt for the less common form people have more right to ask "Why?". If your answer is "Because it sounds more erudite" then probably your usage is indeed "poor writing", because you're a poor writer if you allow such considerations to affect your choice of phrasing.

For the record, I don't think it sounds particularly erudite. It's just a bit dated. But that may be because I'm a Brit, and we still use it much more than Americans.

I'm American from south Louisiana and for me, "to be used of" means "to be used to." It used to annoy my ex when I said, "I'm used of annoying people." "I'm used of it" because I've become acclimated to and it no longer bothers me. Maybe I'm just weird, but I didn't see what he got so worked up about.