officer said you can see it from the door.

No, he didn't. The "when viewed from the door" is to define which side of the body it was on, when viewed from the door. I.e direction relative to the point the body is being viewed from.

since it literally says it could be seen when viewed from the door.

It doesn't. It is stating which side of MM it was on, when viewed from the door i.e the relative direction from point of observation.

The reason it may not have been easily visible is that it was partly under the comforter.

so happened to have an isolated touch DNA on a brass buckle

DNA on the snap button that would have to be touched, with some pr4essure, to open and tehc lose the sheath? Seems logical that would be a most likely spot to find DNA. Also probably the hardest part of the sheath to sterilise of DNA.

Brass and blood together, don't mix

I think that is silver and werewolf blood. In so far as brass may accelerate degradation of DNA, that would only mean that the DNA on the sheath was deposited in a short time frame before the murders given the full profile recovered from the sheath and adequate amount for two different profiles as you noted, As secondary transfer DNA persists for only c 5 hours, that and brass would narrow the time frame for a second person having touched Kohberger then the sheath to a few hours before, when he was out driving alone, so seems to rule out that unlikely explanation.

snap on sheath well how the hell was there enough trace DNA to even get a profile

I've heard DNA profiling requires only a smidge, However, "touch DNA" does require c 200 x more cells for a complete profile, and clearly there was adequate DNA recovered for two complete profiles to be generated in this case.

don't believe there was no blood on the sheath snap

It is clearly stated the DNA in the snap was single source, male and from Kohberger. That precludes victim's blood on the snap.

why under the cover how did it get under the cover

It was partially under the comforter - you'd expect a significant amount of thrashing around during the stabbing, which may explain both how the sheath fell from a pocket and how it was partially under the comforter.

the sheath thing that hook to a belt was it broke

We don't know if the sheath was hooked to a belt - it probably was not.

that time the bodies were there the sheath would have blood on it

The pictures of the mattresses being removed showed the majority of surfaces of those did not have blood, from the obvious stains - so seems quite possible the sheath was resting on an area without blood.

plus the snap would be found open

Maybe it was. But we do know there was no blood on the button, as the DNA there was single source from Kohberger.