Heardwyn is a short woman of tanned and heavily freckled complexion, measuring about five feet and three inches in height and appearing to be no older than twenty. She is of muscular build, befitting the warrior she is, with a few small scars and several calluses indicating a great deal of practice in combat. Her wild, auburn hair tumbles about her shoulders in an untamed mass, and seems resistant to any sort of management other than stuffing it all into a hood. Despite this unusual coloration, her features are decidedly Rohirric, and she has bright blue eyes that would not be uncommon among the people of the Mark. Her demeanor is usually casual despite her now more military-oriented lifestyle, and she is rarely clean, neat, or otherwise presentable unless confronting the formidable Eadgryth.

Heardwyn speaks Westron with a Rohirric accent, but her Rohirric itself is also accented, suggesting that she grew up in an isolated area such as a village, around Western Rohan, near Dunland. Her enunciation is not particularly good, and she often speaks quickly. She also takes quickly to slang and contractions.