According to Dr Sharib:

'Al-Qahhar is the One whose control over everything is perfect and absolute.'

Emulation of the quality of the name requires that one guards against the
machinations of Satan and disobeys his dictates.

Appropriate recitation is effective in removing love of the world from the heart
and overcoming enemies.

see 'The 99 Most Beautiful Names of Allah' by Dr Zahurul Hassan Sharib

Some other references:

Al-Ghazali says that among men the one who subdues his enemies is the
dominator. To subdue the lower self and the passions of the soul is to
dominate. Whoever conquers and subdues his self has conquered all men.

(Al-Ghazali - The Ninety-nine Beautiful Names of God. Trans. Burrel/Daher: ITS: 1992.)

There is a story told by some that Hazrat Ali was offered poison and accepted,
it and when told it could destroy him said he had many enemies within himself
that he was happy to destroy.

So far as man goes this name refers to self-control.

Bismillah ir Rehman ir Rahim
The Subduer, The Victorious, The Dominating One,
The Avenger, The Dominant, The Dominator.
Qur'an 13:16
Say: "Who is the Lord and Sustainer
Of the heavens and the earth?"
Say: "Allah."
Say: "Do ye then take
(For worship) protectors other
Than Him, such as have
No power either for good
Or for harm to themselves?"
Say: "Are the blind equal
With those who see?
Or the depths of darkness
Equal with Light?"
Or do they assign to Allah
Partners who have created
(Anything) as He has created,
So that the creation seemed
To them similair?
Say: "Allah is the Creator
Of all things: He is
The One, the Supreme and Irresistible."
Qul mar-Rabbus-samaa-waati
wal-'arz? Qulil-laah. Qul
'afatta-khaztum-min duu-ni-hiii
'awli-yaaa-'a laa yamli-kuuna
li-'anfusihim naf-'anw-wa laa zarraa?
Qul hal yasta-wil-'a' maa wal-basiir.
'Am hal tasta-wiz-zulumaatu wan-nuur?
'Am ja-'aluu lillaahi shura kaaa-'a
khala-quu ka- khal-qi-hii
fata-shaaba-hal-khalqu 'alay-him?
Qulil-laahu Khaali-qu kulli shay-'inwwa

(Qur'an 13:16)