steeldragons
Steeliest of the dragons
I forgot the name I gave it and it's not something very spectacular. But I once gave out a spear that changed shaft length at will. Wanna be sneaky? Just the tip and handle make it a dagger. Want to keep masses at bay? change to longspear.
Not exectly a magic item, but I ended the last campaign of my group (which was cut short) with them opening a gate that "would fullfill their wishes". The PC's wanted riches and military might, so they got an army of gold and diamont encrusted skeletons.
Hmm, there's two thing I could use again in a new campaign...
I'd say that's a right good magic item. I use that sort of property on magic items all of the time. It's fluffed into the world as "elf made weaponry" from the last/elvin age are almost always enchanted with "retraction/expansion" magics. The one that sticks in my head most is a halberd I gave out that had the retracting/expanding shaft as you describe, so the warrior who had it could use it two-handed as a halberd or spear...or a two-handed battle axe...or shrink it down to single-handed "hand axe" size to fight with an additional weapon or shield on their other hand.
Also, practically all elf-made magical bows (of the upper crusty type elves) have retraction enchantments so they basically shrink down to just the grip, fitting on their belts/no larger than a dagger and growing to full bow (short or long) size when pulled out to use. One elf-prince character has the quiver of his similarly connected to the bow's magic so the quiver and arrows in it shrink down to, like, darts in a hip holster and grow to the needed size when the bow is activated.
And, have to say, the gold army and diamond-encrusted skeletons are a GREAT evocative image/idea. Consider them yoinked!
--SD