The Meaning of Life, the Universe, and Everything.
I don't know of much software that would allow you to do that. I'd recommend trying source SDK and trying hammer editor but I don't really know if that allows you to explicitly create models from the bottom up, say to create your own mesh, joints, etc.
Out of curiousity, why don't you want to use Blender?
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There is nought to fear but the machinations of man