This is one of the swords used by Brad Pitt in the battle between Achilles and Hector.

Several swords like this were used in this scene. This sword in particular was the one used when an accident happened:

Brad Pitt accidently caused a little cut in Eric's face. As Eric Bana said in an interview:

"Despite the physical nature of his roles he says he is 'scar-free, with the exception of the tiniest nick on my nose,' courtesy of Brad Pitt and sustained during the filming of Troy.
'The sword may have been rubber but the blood was real,' he says. Bana's nose was glued together in order to continue filming; there was no time for stitches."