It seems likely no finger-prints were found on the sheath - the defence would very probably have flagged any non-Kohberger prints found and any such prints would likely have associated DNA.
Assuming no prints were on the sheath, what can be inferred?

Kabar USMC sheaths appear to have very smooth, almost "glossy" surfaces which reflect light. Areas of printing/ embossing are very sharp, the outer faces do not look porous/ matt. The surface would likely retain finger-prints well. As a reference, prints can be recovered in many circumstances, even from some fabric surfaces - like towels, shirts.

We could speculate:

• The sheath was cleaned of all prints by the killer
• More outlandish "framing" scenarios whereby Kohberger handled a sterile sheath handed to him are not supported. Why and how would the "real killer" clean off finger-prints and yet leave DNA? And why would anyone intent on framing Kohberger clean his prints (and DNA) from the very areas of the sheath most handled and rely on the snap button only?
• An "innocent" touch DNA scenario whereby Kohberger touched the sheath in a store (or a social setting) is not supported. That requires a weirdly unlikely scenario where the sheath was cleaned thoroughly enough to remove all finger-prints/ DNA of all browsing customers, staff and yet only Kohberger's DNA remained.

A more likely scenario may be:

• Kohberger has higher than average knowledge of DNA forensics from his studies and interests in violent crime. His Criminal Justice courses at De Sales, while not focussing heavily on physical forensics, did cover this area - including a simulation Crime Scene House and forensic evidence collection. Kohberger canvassed, via a research questionnaire a few months before the killings, descriptions from violent criminals of their crimes, including how they prepared.
• Kohberger's knowledge of sterile/ aseptic technique is theoretical and he lacked practical experience. In biomedical labs, medical and manufacturing settings where personal protective equipment (PPE) is used to help maintain aseptic environments those who lack practice often make similar, common, repeated errors - e.g. getting the order of donning PPE wrong such as not putting on a hair-net first (which then has risk of hair potentially transferring to other aseptic protective wear being donned) or not washing hands immediately after putting on shoe protectors before touching any other PPE.
• Kohberger cleaned the sheath thoroughly to remove his finger-prints and DNA, but re-contaminated the sheath in the car or just after entering the house when he opened it -- by touching a surface with a high loading of his own DNA after he put on gloves, such as the steering wheel, door handle or his own nose/ face as he put on/ adjusted his mask.

\"Gloss\" surface of Kabar sheath - reflective

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Smooth surface of USMC Kabar sheath, sharp printing/ embossing

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Hand prints on the 1122 King Road lounge window

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