The Eituhel are measured at 170 cm to 243 cm in height and bear very spindly-to-lean body masses, typically weighing around 145 to 180 pounds at the peak of physical maturity, varying depending on height ratio. All Eituhel have pointed ears, often being very small upon birth, which could grow to as long as 6 inches as they grow and mature. The smallest ear length possible is 3 inches. Eituhel are among the many unique races that do not experience many differences between sexes, with their physical features being virtually identical in most cases. A few, albeit very subtle, key differences are found in wing patterns, with male having thinner veins, if applicable, and lighter colors compared to female. It is also said that females tend to be a bit larger, but this is not completely proven. Their fey ancestry binds the Eituhel to the changing seasons when born, separating them by summer, spring, autumn, and winter at random. Depending on the bound season, an Eituhel's temperament and coloration are influenced.

Eituhels come in a wide variety of skin colors, with the seasons only corresponding to different undertones. Those bound by autumn and summer tend to have warm undertones, while winter and spring-bound elves have cool undertones. This similarly applies to hair and eye color, which can potentially take on many vibrant shades that could be thought of as unnatural by human standards.

Temperament and behavior are not completely exclusive to the seasons, but certain traits are commonly found among them. Usually, spring Eituhel are nurturing and playful, summer Eituhel are assertive and energetic, autumn Eituhel are thoughtful and wise, and winter Eituhel are withdrawn and stoic.

The Eituhel age at the same rate as humans, reaching physical maturity at 25 before their aging drastically slows from that point onward. Despite their functionally indefinite aging, at a certain threshold around the age of 200, they begin to experience a severe mental decline, causing them to gradually enter a state of insanity. The longest an Eituhel has been recorded to live was at the age of 300 before dying from their own doing. Due to their heightened senses, Eituhels are adventurous and curious by nature, often exploring far corners of the land to find knowledge through their experiences. This also makes them impulsive, rarely dying of old age and more as a result of unfortunate escapades. They do not need sleep to replenish their energy, but instead “roost” in a safe and quiet area while they enter a state of torpor, which can last for days on end at maximum. During this time, their physiological activities decrease, reducing body temperature and metabolism. However, their senses and consciousness remain active enough to act towards danger if need be

While mostly humanoid, Eituhel exist on a spectrum of lepidopteran features, some being more obvious while others are almost non-existent. The most common trait among these features is the presence of long, feathery or club-tipped antennae stemming from the top of the head. These antennae help to keep an Eituhel's balance, while also offering them a greater sense of smell.

Secondarily, flightless, varyingly patterned wings grow from the back in different sizes depending on the individual, ranging from being large enough to cover the entire body to barely the size of a palm. Underdeveloped wings are also not uncommon, often falling off during adolescence and creating back scars that persist throughout ones life. These wings are composed of a thin layer of chitin that is covered by tiny, reflective scales, making them relatively durable for everyday life. While flightless, they typically serve as a means of emotional expression, camouflage, insulation, and protection against the elements, supplementing the lack of body fat. Despite their durability, wings are prone to ripping when placed under excessive stress. Although it is possible to sew them back together, this may weaken the protective properties of the wing and cause permanent scarring.

Rarely, Eituhel can also be born with insectoid limbs, the ends of which hold taste receptors that can make an individual more sensitive to their environment. The same holds for Eituhel who are born with compound eyes, the only difference being that sensitivity is vision-based. The last characteristic that is biologically possible is chitin-based fur, typically present in tufts around the neck and joint areas. This is usually common among Eituhel who live in colder climates, and require additional insulation to maintain efficient movement.