I don't know how I overlooked this topic...
I am a professional health physicist (radiation safety) by trade with a few degrees in both nuclear engineering and health physics. Ask me about my research sometime
. I've handled quite a bit of U, DU, Pu and a host of other isotopes. From what I've seen, this material would not be very useful a s a knife. Depending what alloy you have, it may not even be machinable, let alone forgeable.
Depleted does not mean "not radioactive", it simply means depleted in U-235 isotope (the fissionable one that makes a warhead go BOOM). Ie, the uranium is for the most part all U-238 and non-fissionable. While source material (uranium ore, minerals and the like) have stipulations for private "ownership", pure U-238 is indeed a regulated material, although there are all levels of regulation. This will depend on total amount, chemical form, and use. These seem to change yearly. Uranium acetate and nitrate are used to etch concrete to test for stress fractures and such. Uranium metal is used for counter balance where lead isn't structurally useful. It's still used as a coloring agent for glassware and tile. Regardless whether you're allowed to have a hunk of pure U-238 or not...I personally wouldn't want it sitting around my house.
As a large hunk of solid metal, it's fairly harmless unless you sleep with it taped to your skin, or drop it on your foot. Most radiation coming off of this is not penetrating and it's not much of an external hazard. As dust or small shavings, it's bad news. Radiation isn't the biggest issue with uranium. In fact, it's the only element whose radiation limits are actually based on acute heavy-metal toxicity to the kidneys and not radiation damage. If you were to grind this into a dust, you would probably start a fire in your shop. While you may not inhale enough to cause any noticeable health effects...the fire issue is significant. You can't put out a U-fire with water, either. You'd pretty much turn your shop into a superfund site, as well, due to the dust left behind. Transporting the material from a foriegn country to the USA is a whole other can o' worms you wouldn't want to get caught up in.
Forging uranium....when I went to the plant who makes the tank penetrators, I believe the ingots were heated to about 2800* for the extrusion process in a completely inert environment. I don't think shoving a bar into a forge would really be a good idea.
In short.....uranium knives, swords...bad idea.
P.S. Heat does not make something more radioactive. Half-life/specific activity is a physical constant. A 1 kg bar of uranium will be just as radioactive at -300*F as at + 3000*F.
I collect uranium bearing minerals, rocks, fossils, glassware, etc. Just another one of my wierd hobbies. These are quite fun with a radiation detector. Take a geiger counter through an antique store some day...you might be suprised at how much stuff will get a good response!