Scars in a dream usually represent past pain that's healed into memory rather than an open wound -- proof that you got through something difficult. Noticing a new scar can point to resilience you're only now recognizing, while an old one resurfacing may reflect a memory quietly asking to be revisited.
Don't demand harmony from Mars nor fracture from Venus; be rigorous on this and never divert a celestial body from its path. - Picatrix (Andalusia, ~1000.AD)