you can't use that satin finish SE if you don't want to scratch it. as for the sheath that model has clearance built into it and locks up on the handle. your knife was fitting to it's sheath and was inspected and shipped scratch free. some makers sheaths are tighter and some looser but dirty kydex will scratch your knife as well as dirty leather.
my advice is not to worry about it. keep your knife clean and you can run water down your sheath to clean it too. use a large pipe cleaner or a ruler wrapped with a light towel to knock out the dirt.
now as for your satin blade I'll tell you what i do but please try to keep it a secret.
get some green sheets of scotch bright, they make them pretty big, like 8x10"
clean your blade with good old regular gasoline along with the handle.
now with the scotch bright on the counter, wipe your blade from spine to edge light or heavy, however you like.
spine to edge, just like the final polish or grinding was done.
light scratches are easy, heavy ones take more pressure and longer.
after you get good and tired of babying your user then go use it and stop worrying about how it looks.
again, for sap, pitch and that stuff just use gas, diesel or lighter fluid to clean the whole damned knife.
soap and water for blood.
a word of caution!!! zombie blood is not to be messed with, unlike in the movies you don't want this walking dead smelly corpuscle crap splattered in your face or in a cut. keep it out of your sheath.
or before you know it you'll be stumbling around, dragging one foot and mumbling 'brains, Brains, I WANT BRAINS'
no joke, not funny, i'm serious about this stuff.....
i ALWAYS buy a pair and a spare....
.