My favorite is the Green Fugue, an ancient Chinese Sword that will duplicate its user while in combat. Practical upshot of this weapon is that you get to play two identical versions of yourself in combat where otherwise you might be overpowered. The _downside_ is that if one of them dies...well, that one is just as much you as the other. Time to reach for a new character sheet.

Another is a gun that bleeds chi from the user for the rest of the session in return for embuing its target with that person's memories from the previous significant shift. It only works on people who've not been exposed to the Netherworld. It was said to have been made by The Lover, one of the original Silver Dragons, when he had been Unstuck but could not bear to bring his true love into the Secret War.

SYL

As to the items you mention, and one or two others in Iron & Silk, i think GM judgement is the order of the day. Some of the items are non-magical and could be readily available (dependant on your juncture) yet have interesting and powerful abilities. If your PC's have read iron & silk they may expect those abilities. They then get a hell of a surprise when the items that they hunted down don't do what they expect, or do something completely different (be as mean as you like).

I personally would not let all items of a given type have the abilities listed in the book. Maybe a particularly old and valuable (and thus fragile) Geomancy tablet would have better and more varied powers, whereas a shiny new one from a chinatown gift store does nothing special at all (except go thunk when you whack someboby with it).