Answer:
I can be found after you remove 6 letters from BSAINXLEATNTEARS
What gets sharper the more you use it?
I am a portal to another world which you cannot enter. Only you can see me but I can't see you.
You bind me and I walk. You loosen me and I stop. What am I?
I am known for my natural tuxedo and marching. What am I?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.