Scars are intended to accumulate rather than disappear at the next heal. They are vital history, visible character change, something NPCs can react to and a spendable source for magic.
That overlap is the interesting part. A player choosing power is also choosing what becomes visible and what history remains on the character. A survival consequence can later become capability without ceasing to be a consequence.
The implementation still needs careful limits—the concept would collapse if scars became just another renewable mana bar—but the durable rule is that one history should drive all four readings.