If you make one for yourself, and do not intend to sell it, there is NO copyright problem. The maker of said knife also has NO copyright problem. The onus of design is on you, not the maker. Now if your buddies, and people on here start wanting them, that's a whole different story. But if you make yourself one knife, there is no problem with it.
BTW.... I am a graphic artist and I have been dealing with copyright laws for 25 years. It all goes to profitability, and in this case there is 0$. But again, and it can't be stated enough....it's YOUR knife, it WOULD be illegal to sell it at any time.
Now, go have it made, we all want to gawk at it. LOL