uncommon weapons form (sword and trident)

[Titus Thurinus]

I saw a picture a while back that depicted a gladiator wielding a standard looking gladius in his right hand and a trident with what looked like a small leaf bladed spear head on the bottom in his left. I have been trying to find anything that documents this style of fighting to no avail. And I cannot find the picture again either. Can anyone tell me if something like this is documentable and point me in the right direction?

I know that any number of weapons combinations must have been used in the effort to entertain but I have not seen anything else that depicted this particular combination.