Unless there is some kind of documentation to indicate when the handles were replaced and when the tip was re-ground, the modifications could just as easily have been done last year, ten years ago, twenty years ago, etc. None of which would make those modifications authentic "trench art" or increase the knifes value on the antique collectors market.
Kinda like if someone gave you an original KABAR with the tip broke off. It could have been broken off during hand to hand combat between a Marine and a Japanese soldier on Iwo Jima. Or it could have been bought brand new as military surplus by a civilian and had the tip broken off when the owner used it to pry open a paint can.
Collectors come in a wide variety. Some just like to collect cool looking stuff and don't care about authenticity or provenance, some will only buy items in there original, un-modified and un-restored condition, and some will pay big bucks if an antique weapon comes with proof and documentation. Serious collectors are very demanding when it comes to proof and documentation because there are a lot of fakes out there.