sliver of wood, etc.  One last thing; I thought it was less honorable to ask
someone to help one kill himself...  and if Ranma really really loved his
friends, he would do it himself.

No, it's not. Someone always had a 'second' who chopped the guy's head off
after he slits his stomach. This is so that he doesn't take forever to die.
Usually it would be the guy's mentor or someone close to him. In this case,
it was Ranma's mother, who would be doing that job, anyway (see in the
manga, she's the one with the sword, standing over them, while Ranma and
his dad kneel down with the small knife/dagger things at their stomachs?
That's because she's the one who would chop off their heads, to finish the
job.)

Kun-chan...