Quintus Honorius Romanus aka Taurus, our hero in James Duffy's Sand of the Arena, mostly fights as a Thracian. This fighter is described in Duffy's introduction to his book (Download duffy_intro.pdf), as
A lightly armored fighter carrying a small square shield (parmula) and curved sword (sica). His helmet crest often bore the image of a griffin fixed to the front.
Roman Gladiatorial Games from CUNY shows an image on this page, the third one down on the right. If you click on it, you can clearly see the crested helmet. This image is also on the informative Culture I page at the same website.
Whereas in my photos (copyright © Irene Hahn) from the Gladiator Mosaic in Bad Kreuznach the helmet on each is much
less defined. However, here one can clearly see the sica, even if the form is more square than rounded.
Bill Thayer Jim Grout has a page with a longer description, with a photo of the same scene above but more professional than mine (although I think my colors are closer to the original) and pictures of greaves and the helmet.
And from Wikimedia Commons this oil lamp from the Louvre; click on image for large size & photo origin: