The Mameluke is a replica of the sword given to Marine LT Pressley O'Bannon after the defeat of the Barbary Coast pirates near Tripoli. Marine officers wear the sword with dress blues/whites when ceremony and protocol dictates.
I was not a Marine officer, but one that was getting out gave me his sword.

The Marine staff NCO sword is plainer, and is only used for ceremonies and parades.
I was a staff NCO, and it was a PITA.

Drilling (marching, etc) with a sword is part of Marine officer and staff NCO training that is archaic and I've never figured out a use for. I suppose it looks good on the TV commercials, but doing it precisely takes a ton of practice time that I always thought was better used chasing fun.

I'm pretty sure the Army has a sword, I've heard that soldier's play with their swords a lot....

As far as a weapon, I'm not sure mine would cut butter, and it's very hard to run with.