Clark & Lex are talking about Alexander the Great's armor.
Clark: Can't exactly see myself going
into battle with that on my chest.
Lex: Darker times call for darker methods.
His opponents thought he was invincible.
I know 'dark' has several meanings. Is it meant obscure here?
As in mystical times need their mystical methods?

I'd think of it more as 'more serious, more dangerous, more difficult'.

Thanks for your opinion, Clive!