I don't know about the knife, but I seriously doubt the sword was his. It is most likely the first decade of the 19th century. He wouldn't carry it and I doubt if he would keep such a ratty sword as keepsake.
Custer was fond of a sword that was captured from a Confederate during the War. That one is in the Little Big Horn visitor's Center now. I have a vague memory of Custer being fascinated with soldiering even when he was a kid. Maybe that sword belonged to him in childhood or adolescence. It predates his brief lifetime by a good bit.