What does It's school, then work, and then life that just sharpens the blade mean?

Question

Its in a song by Carbon Leaf called "What about everything" any ideas on the meaning

Answer 1

sharpen the blade means honing, fine tuning, improving the edge, making it better

It seems like the meaning of your question is that people mature in school, work, and life. This maturing process is what is referred to as sharpening the blade. You are constantly growing in knowledge, personality, commitment, confidence, self esteem, trustworthiness, reliability and all those other characteristics that form the "you" that you are. Its a process, and the more experiences and education you get in all kinds of things, the more interesting and sharp you are.