Significance of the beard
Most often neglected by players is the nature of the Beard, and what it represents in fictional storytelling. The Beard often symbolizes the ragged wear and tear of the character's previous challenge. Through a change within themselves, and the loss of something important, the character no longer cares for menial things like grooming. They have, in essence, lost all ability to give a crap. While this is often misconstrued by gamers as an attempt to make a character "more masculine." it is actually a storytelling shorthand for showing the strife the character has endured to this point.
Other tell-tale signs of a well-worn character who has, in fact, "seen some shit" is a slight sagging under the eyes, bushy hair cut, and a generally more gruff demeanor. Changes to posture can be evident as well, such as Sam Fisher in the fifth Splinter Cell title, "Conviction" adopting a slightly hunched over pose, reflective of his age as well as his current emotional state. The Bearded Sequel is but one of many ways for creators to show that the character has changed, and not for the better.