Characters
Don’t worry, I’m not gonna start any sword fights. I’m over that phase.
— Mal ‧ Firefly

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Mal reassures everyone that the sword fighting is behind him. He talks about it like a phase, a habit outgrown from earlier days. The humour is in treating swordplay as something he can promise to keep in check.
Context reviewed