It might be argued that a man who employs this kind of skill with words for immoral purposes can do great harm, but the same goes for everything good except for virtue, and it goes above all for the most valuable things, such as strength, health, and generalship. After all, moral use of these things can do the greatest good, and immoral use the greatest harm.

[εἰ δ᾽ ὅτι μεγάλα βλάψειεν ἂν ὁ χρώμενος ἀδίκως τῇ τοιαύτῃ δυνάμει τῶν λόγων, τοῦτό γε κοινόν ἐστι κατὰ πάντων τῶν ἀγαθῶν πλὴν ἀρετῆς, καὶ μάλιστα κατὰ τῶν χρησιμωτάτων, οἷον ἰσχύος ὑγιείας πλούτου στρατηγίας: τούτοις γὰρ ἄν τις ὠφελήσειεν τὰ μέγιστα χρώμενος δικαίως καὶ βλάψειεν ἀδίκως.]

Aristotle (384-322 BC) Greek philosopher

Rhetoric [Ῥητορική; Ars Rhetorica], Book 1, ch. 1, sec. 13 (1.1.13) / 1355b (350 BC) [tr. Waterfield (2018)]
    (Source)

(Source (Greek)). Alternate translations:

But if it be urged that a man, using such a power of words for an unjust purpose, would do much harm, this is common to all the goods, with the exception of virtue; and especially in the case of the most useful, as for instance strength, health, wealth, and command: for by the right use of these a man may do very much good, and by the wrong very much harm.
[Source (1847)]

If, however, any one should object that a person, unfairly availing himself of such powers of speaking, may be, in a very high degree, injurious; this is an objection which will like in some degree against every good indiscriminately, except virtue; and with especial force against those which are most advantageous, as strength, health, wealth, and generalship. Because employing these fairly, a person may be beneficial in points of the highest importance; and by employing them unfairly may be equally injurious.
[tr. Buckley (1850)]

If it is objected that the abuser of the rhetorical faculty can do great mischief, this, at any rate, applies to all good things except virtue, and especially to the most useful things, as strength, health, wealth, generalship. By the right use of these things a man may do the greatest good, and by the unjust use, the greatest mischief.
[tr. Jebb (1873)]

And if it be objected that one who uses such power of speech unjustly might do great harm, that is a charge which may be made in common against all good things except virtue, and above all against the things that are most useful, as strength, health, wealth, generalship. A man can confer the greatest of benefits by a right use of these, and inflict the greatest of injuries by using them wrongly.
[tr. Roberts (1924)]

If it is argued that one who makes an unfair use of such faculty of speech may do a great deal of harm, this objection applies equally to all good things except virtue, and above all to those things which are most useful, such as strength, health, wealth, generalship; for as these, rightly used, may be of the greatest benefit, so, wrongly used, they may do an equal amount of harm.
[tr. Freese (1926)]

And if someone using such a capacity for argument should do great harm, this at least, is common to all good things -- except virtue -- and especially so in the case of the most useful things, such as strength, health, wealth, and generalship. For someone using these things justly would perform the greatest benefits -- and unjustly, the greatest harm.
[tr. Bartlett (2019)]