Mechs

Mechs first made their appearance in Caldonia a few decades after the Feren War. At first used exclusively by duelists and hobbyists, the obvious tactical advantages that mechs potentially represented were not ignored by the military, and standing army of Caldonia now boasts 2 full companies of mechs, most members of which are constantly rotating temporary duty to other units.
"Mech" is common parlance for any piloted, mechanical device of a loosely humanoid configuration capable primarily used for combat either by the devices physical power or attached firearms and other weaponry. There are, currently, some general mech types, inconsistently categorized by appearance, function, or capability, but there arere no defined characteristics of different mechs. One-size does not only not fit all, one-size basically fits one. There is no such thing as a "stock" mech or a base kit. As such, fights between mechs are at least as much a measure of the engineer who put it together as the skills of the pilot, and in fighting tournaments, generally the engineer and the pilot are one and the same.
Some engineers design mechs for raw strength, and these mechs can generally be identified because they will have a Really Big Gun (RBG, in tourney lingo) attached to one or more shoulders or arms, possibly in the center of the chest. Other engineers prefer speed and maneuverability, and such mechs are characterized by having much narrower phenotypes than the typically heavyset mechs that are built for strength. This seems natural, given the tradeoffs required to balance weight, size, and power. Some clever engineers have built mechs that defy the stereotypical appearance of the capabilities they are striving for, but the majority of mech builders feel that the limited advantages for such a trick are far outweighed by the difficulty of engineering against type.
The Caldonian military favors endurance in their mechs. This tends to align more with RBGs and raw power, but it is not unusual to see more agile models that can take the punishment the military use can dish out. These mechs don't just stand there and take the hits, but sometimes that's what's required to cover a withdrawal.
Military mechs always have closed cockpit designs, which is not universal in tournament play. Tournaments almost universally disallow attacking the pilot directly, so some pilots and engineers like open cockpits, or even "ride on top" designs, especially if they like to show off. However, accidents happen even when pilots are scrupulous about following the rules, which makes closed cockpits much safer.