Most meele wapons rely on the user's ability to touch any part of it. For clasical wapons, make the blade phased but have a spine that can be touched by the user. That way, a double edged sward doesn't feal so double eged anymore but can be pushed at it's end to greatly increace force.
But we can take this further: Build a staff that is sourrounded by pahsed blades. The wielder's hands are mostly safe since the blades reach further than them. Normally when fighing against staffs, one tryes to (block and) safely grab it and abuse the fact that the attacker holds on to it. But wow your enemies can't do this since they can't safely grab a blade and they can't crush your hands that are safe within the blades (or even a phase metal cylinder around the solid staff but that's going to be quite heavy).
For onehanded weapons, just forge a spiked (hollow if you want to safe weight) sphere around a solid core so that your hands are completely covered by the sphere. Don't connect them to your vambraces though or you might get disarmed eventually. But that's about it. If you add phased blades to pretty much any wapon (including nunchucks) that would likely cut the user if not phased, you would need to fight naked. Imagine a sward that has a medium sized, solid staff to handle it and has double edged blades pointing in all directions. You could "stab yourself" to reach enemys behind you, spin it around to create a deadly sphere and do many other things that are theoreticly possible but humanly impossible to coordniate. There are hundreds of possibilities but most of them can't be used since the weapns grow heavier, you can't use them with armor and most of the moves you can imagine can't be coordinated in the heat of a battle.
To hide a dagger in your body like suggestet by sdrawkcabdear would be handy for assasins but if you can't grab the handle, it would be hard to actually use it. That's why you would have to hide the handle e.g. in your mouth. or invent a new shape of dagger handle that resembles a knuckle-duster and is flat enought to be hid beneath your cloths.
[Edit:] You might also use this for medicine and/or turture. Make someone forge a long handle and add a solid ball at the end. Insert the ball and performe a haptic gastroscopy/coloscopy - or torture them by forcefully shake the handle or do any number of similar things. I don't want to go into this but the possibilities are only limited by your imaginativeness (and cruelty).