Virtue ethics often relies on appeal to authority and circular logic.
There's a cause and effect to it that really works. One's life doesn't simply improve if they're putting on a shit show, but with virtuous practices the results grant one success and piece of mind.
Were ancient Athenians correct in viewing slave-owning aristocrats as virtuous, or was it systemic injustice?
Sure.
In the modern day when people think about slaves, they think about how, some, white people treated the negros when they had slavery in the US.
The Bible is cool with slave owning too.
In ancient times, slavery was a choice for some. It isn't free to keep slaves, they have to be looked after too. They need food and water, need to be bathed. Need clothing, and lodging. If these things weren't met it would bring shame to the slave owner.
Also having slaves doesn't mean treating them like sub humans. Many owners and slaves would love one another like family.
In short. Slavery is along the lines of: You look after me, and I'll look after you.
It's still a thing today. We call it a job. The only difference is we can fuck off at any time, while the boss can replace his workers. Either way it'll cost the head money.
In the modern day, having a slave ain't cheap.
If a rich person took a homeless person off the street, and said you can live with me if you do chores, you'll get a room, clean clothes, some time off, 3 meals a day. That's the same thing as slavery. And it's a sweet freakin deal isn't it ? Just don't say the S word, as it reminds people of how some ( not all ) white people treated negroids.
It is often taught that to be virtuous requires being like a virtuous person. E.g Be like Gandhi. Let's not even get into his racist campaign against blacks, believing they didn't deserve rights or suggesting suicide as a cure for rape victims.
Gandhi said blacks in Africa were were savages. He's partially right. Even today look at how they kill white people in Africa.
Gandhi was just an imperfect human being. Christ is King.
A virtuous person is often considered virtuous because they do virtuous things. This is circular reasoning (a common logical fallacy,) assuming an arguments premise/claim assumes the truth of its conclusion. It assumes already what it claims to prove.
E.g. "Virtue is a state of character concerned with choice… as the prudent man (phronimos) would determine it.” -Aristotle
But: Who is the phronimos?
→ “The one who exhibits virtue in action.”
This is circular reasoning with no external standard which Greek elites used to justify slavery.
There are many problems with virtue ethics.
That's simply an opinion.
As far as slavery goes. It's advised to treat slaves with kindness. Like Dr. King Schultz in the movie Django. He acquired Django and between them they were partners and friends, Django was a "freemen" and had a great deal of respect for one another. The world is filled with homelessness. They world would be a better place if people took in good people and looked after them in exchange for their services. And there would have to be some benefit to keeping someone fed, sheltered and clean in all fairness.
It happens and it's good for both parties as long as no one is a dick about it.