I find the legion's avoidance of modern technology ridiculous. The things that made the Roman armies successful was their discipline, tactics and advanced military technology. If they conquered someone with better technology they adopted it (e.g. Chain Mail from the Gauls). Caesar even states they eschew medical technology (apart from his auto-doc for favoured people). Roman armies had highly skilled battlefield surgeons. Relying on hoards of suicidal fanatics won't win any battles against an organised opposition with better firepower. The Legion just wouldn't be a credible threat to anyone, particularly the NCR.
Just something I've posted http://www.gamesas.com/index.php?/topic/1147247-factions-you-would-like-to-see-in-fallout-4/page__st__40
Do you mean they should have been a Roman version along these lines?
The Spartans
In many cases identical to ancient Sparta, meaning they are a militaristic and agricultural faction. They also try not to waste anything (like their http://en.wikipedia.org/wiki/Black_soup. As a result their faction unique weapons do more damage, are slightly more accurate and are more durable but suffer from a lower firing rate and are more expensive. While you might think they're similar to the Legion they are very different, because
Weapons that are unique to their faction
Minihttp://en.wikipedia.org/wiki/Phalanx_CIWS, uses 5mm ammo, repairs with minigun. Possibly with a 20mm Phalanx as unusable static defense eyecandy.
http://en.wikipedia.org/wiki/Tartarus or http://en.wikipedia.org/wiki/Ixion, uses flamer fuel, repairs with flamer/incinerator
http://en.wikipedia.org/wiki/Gastraphetes, uses MF Cells, repairs with Plasma Rifle like http://starwars.wikia.com/wiki/Bowcaster
Herakles power fist
http://en.wikipedia.org/wiki/Dory_(spear), repairs with thermic lance
Just to name a few weapons, IMO, they could use a normal rifle as well, but I haven't been able to find anything. Instead of the vertibird they use the http://starwars.wikia.com/wiki/Lambda-class_T-4a_shuttle for transportation, but IMO it has to lose the tail, so it look more like an upsidedown V, maybe make it a crossover between the SW shuttle and http://memory-alpha.org/wiki/File:Klingon_Bird-of-Prey.jpg, but IMO the latter one Should have the wings in a more downward angle.