Fitness

Asymmetry can indicate imbalance in some way. Could be worth evaluating how you handle weight in each arm, maybe record clips if you can?

I've developed pretty bad callouses over the years, though honestly they're handy for certain types of work, particularly deadlift and barbell row. Helps for specific instruments like the guitar or bass, and tasks like sewing.

Climbers tend to file theirs down, I gather it's detrimental to their grip. You may find this helpful though personally I find them valuable for weightlifting. If this is causing acute discomfort you may want to look into using gloves or chalk?