"startling how im the only person on this site with an actual human soul. you would think the other guys on here have one, but no" - dril
All of Pat's fetters are a reaction to the previous Fetter (except for, of course, The Useless Princess, because she's stage-one). The Heroic Knight is a reaction to The Angry Witch. The Heroic Knight is formed out of Pat's deep regret from The Angry Witch's actions, symbolized by the dried blood coating her hands. The past cannot be undone, and she has done unforgivable actions, and so she cannot wash off the blood. But just because she regrets and tries to make amends, doesn't mean that the anger is gone. It never will be gone. But she can control it. Whenever she gets the urge to act out her anger, the blood becomes fresh on it's own.
But The Heroic Knight is also formed out of Pat's desire to save and inspire everyone, and to become noble and good. It is why she is called The Heroic Knight. It is why she protects the people of her realm.
As fearsome as "The Knight will fucking kill you if you piss her off" sounds, The Heroic Knight, unlike The Angry Witch, actually has a degree of control over her desire to act out her anger and very much regrets it whenever she acts out her rage. Mind you--this doesn't make her lashing out okay at all, but at least she regrets it and will make every effort she can to stop, unlike The Angry Witch.
She generally is very cheerful and upbeat, as long as you ignore the perpetual dried blood on her hands (she really hates it when you bring it up) or the smell of death that pops up whenever she's upset. Or the cooking smell of meat that shows up whenever she gets furiously angry.
Unlike The Angry Witch's gnarled forest, the kingdom of The Heroic Knight is actually crisp and clear and sunny. It is bright and hospitable, and full of cheer. There's always a celebration somewhere in the realm. It's kind of like Disneyland. There are various small villages scattered about the land around a tall, white castle. Here is where The Heroic Knight resides.
[with mistakes and other fetters]
The Heroic Knight's true name, Edelweiss, is a flower that is infamous for growing only in the high altituides of mountainous areas. They do not propagate by seeding, and so they cannot be cultivated normally. Because of the harsh enviornment they live in, many perished attempting to retrieve the flowers. For this reason they became a symbol for courage and daring. To have an Eidelweiss flower was a medal of honor, as it was proof that you had survived the worst of the harsh mountain Alps. Their white color is a symbol of nobility. For a suitor to present a bonquet of these flowers meant that he was serious, as well as courageous.
The Heroic Knight, while courageously defending the citizens of her land, is also incredibly noble compared to the previous stage fetter, The Angry Witch. The Heroic Knight is kind (she really only becomes cruel when angry, and even then she spends a great deal of effort controlling herself), has high moral standards and integrity (only acting out when they have been violated, compared to The Angry Witch, who lashed out in fear), and is honorable (to a degree; if they feel that there is no way to effectively deal with a problem honorably, they will resort to trickery, and lying also doesn't count against her moral code).