"Scar tissue typically fades after 6-18 months. Facial ones can take 12-18 months." He trails off, seemingly holding the majority of the conversation with himself. Speaking up for the final verdict as he attempts to seem casual on his abrupt interjection. An attempt to ease your conscience on the idea of permanent damage. "They typically fade eventually."
Hitting you with a sledge hammer would've probably been more subtle.
Ever since your run in with Savitar and the subsequent strike from speed force lightning, you've had scars. The bolts of lightning had been alive with sparks, snarling and roaring with energy as they traveled through your body. You were lucky you hadn't dropped dead then and there.
At first they'd been raw agonizing wounds that had been resistant to your hyper-active healing. Then they'd been brutal scars, heavily discoloured and drawing in stares at any visible inch of them. They covered an obscene amount of skin, a map that followed the consequences of your initial rambunctious nature that had led you to meddle in affairs that Barry had practically begged and pleaded against you about.
You're still a teen. Still scampering around in a high school with judgmental peers. Still stared at by your elders who coo sympathetic remarks at you while badly hiding their grimaces.
He has no intention of following their examples. If he's talking to you, his eyeline meets yours instead of dipping to follow the stigmata of scars that peek from under the masks and longer clothes you've begun wearing. He's donated a few older work shirts to your cause as well.
He doesn't think you should feel the need to cover them up, but he also isn't going to try and force you to show more. It's your choice to make, not his.