These units represent the absolute pinnacle of armored unit performance. They all share multiple fields within which they excel, combining amazing statlines with exceptional personal weapons and skills. Their lack of exploitable weaknesses makes them reliable in all situations, and perfect for dominating the Arena either solo or with a squad.
These units are close to the units in Tier 1, but lack something which prevents them from being among the best. An exploitable weakness, more niche value, lower stat total or lack of personal weapon are examples. However, they only lack compared to the best-- with some support, they can perform just as well as those above them.
Units in Tier 3 all have a weakness or two that stops them from outright dominance. Many of these units have a low defensive stat, lack a personal weapon (or a good one) or simply lower stats than those in higher tiers. With support these units can be a powerful force on the field, but still lack the strengths of those in Tier 1 and 2.
Tier 4 units are held back by their lack of personal weapons or skills, mediocre stat spreads, or a lower BST total than those in higher tiers. These units have little niche, and are often cursed by low Attack, a factor which makes it very hard for them to pierce the defenses of other armor. While they are still very strong compared to all units, these guys often lose crucial same-color matchups and rely on heavy team support to perform on par with those in higher tiers.