I was looking through stuff and I found this old arena map that this Hammer Tutorial had you do (The Project Tutorials by Shrade www.halflifemapping.com). So I thought I'd expand it a lot and modify it and make it for CS:S. It's a rather fun knife map.
smartedit off
weapon_* 1
* is the weapon you want spawned
and you might have to add:
targetname knife
spawnflags 0