Often used as a phallic image... eh?

Not just used, but even named after. The roman word for penis and sword were the same word.

Gladius.

Imagine what Gladiators (people who were associated with erect penises, if I remember this documentary I was watching correctly) had running through their minds when someone was running at them.

"I'm going to stab your head of!"

"With what?"

"With my penis!"
or alternately
"With my sword!"

Things are a little different... out here.