Seems to be original parts to me but as Kevin says the pictures are non conclusive.
Probably somewhere around 5% of daggers are not with maker mark.
I really wouldn't bother with this unless it is very cheap and you have pity for it. The grip will be loose from when the plaster was broken from the tang when it was removed. No amount of washers will make it tight again. It's a wonder the celluloid didn't crack.
Could be refitted with fresh plaster to make a permanent repair.

War is when your government tells you who the enemy is.
Revolution is when you figure it out for yourself.