I've seen a few different books with the title 'A Blade Reborn' floating around, so I'm going to assume you're asking about the webnovel by Splith, which I've followed for a while. The protagonist is named Aestrid. She's fascinating because she starts so low – a retired, once-disgraced swordmaster living as a village blacksmith, her spirit broken and her legendary blade 'Vermillion' just gathering dust. The initial drive is pure survival and a buried sense of duty. Her secluded village is attacked, and she's forced to pick up the sword again to protect the only home she has left. It's not some grand destiny calling; it's desperation.
What really gets her going later, though, is the slow rekindling of her own self-worth. She's haunted by a past failure that got her comrades killed, and a big part of her journey is confronting that guilt. The drive shifts from external threat to an internal need for redemption. She isn't trying to become the world's greatest again; she's trying to become someone who can look her reflection in the eye without flinching. The relationships she builds with a new, ragtag group of allies – a cynical scout, an overly earnest apprentice – chip away at her isolation. Honestly, the moments where she hesitantly starts teaching the kid a few basic stances are more compelling to me than the big fight scenes. Her motivation feels painfully human.
The magic system ties into it nicely. Her sword absorbs the 'essence' of worthy foes she defeats, not just to get stronger, but to literally piece together fragments of lost knowledge and history. So her quest becomes an archaeological one, too, driven by curiosity about what really happened in the wars she fought in. It's a clever way to link power progression with uncovering personal and world history. By the latest chapters, her drive is a messy blend: protecting her new family, uncovering the truth behind her old betrayal, and a quiet, personal vow to finish the job she failed decades ago. It's less about being a hero and more about being a complete person again, which I find way more relatable.