Bartimaeus, just a point, materials for weapons have to be period realistic, so your shield won't literally be able to stop a 50cal round because that's impossible. Though it won't matter, as an ordinary shield would be resistant enough versus anything else from the period.

The same goes for your spear, it can be as sharp as steel, and an ordinary steel spear probably could pierce through plate mail, but don't expect it to be above realistic standards.

It's also completely up to you, but your character is somewhat overloaded for a Gladiator at this point. With a spear and shield and a sword presumably at their hip it would be difficult to also carry three Bolas and two Javelins.