As has been pointed out it appears that any blade in Seattle is against the law. As fas as grinding an existing blade down there are a couple of things to consider. First if you grind slowly and only take off small areas at a time the metal will not get hot enough to change the metallurgy. Should the blade get too hot dipping it in cold water immediately will hold the temper. Just grind slowly and grind the entire length of the blade to avoid build up in one area. Lastly since the blade is decorative only and you aren't planning to go into battle with it in your fist it doesn't really matter is the temper changes since it should always be tucked into your hose anyway.