The one piece multitools that include blades just seem a little dangerous to me, I realize there are safe ways to use them but I'm still not fond of them. I'd rather my bladed multitools have closable blades. I also like my "OPMT's" to be able to go in the court house and similar places with me so I'm not totally without any tools. This being said, my two favorite OPMT's are the Gerber Shard and the NiteIze DoohicKey. The DoohicKey does have a "box cutter" semi-sharpened point. Leatherman makes a few very cool looking one piece tools but I haven't tried any of them out yet.
One thing to note on my two favorites- I carry both on my key ring, because the phillips driver on the Shard is very good at turning a #2 screw unless it is in too tightly; while sometimes I have really needed the wrench sizes on the DoohicKey. The Shard's bottle opener also grips the cap much better, I've never had it slip; and the prybar can and will pull nails better. I can't always have my ST300 with me unfortunately!
I'm not trying to sway you against OPMT's with blades, I'm just offering up some suggestions since nobody has chimed in yet. If you liked those, I'd imagine a sharp edge could be added to one easy enough and a Kydex sheath molded for it. Considering they are hardened enough to be used as a prybar and screwdriver, they would probably hold an edge good enough for occasional use.
