I've always wanted to trade characters and have brought it up to the mods in the past.
A lot of my guys are just for dueling so if I could just get the end game char (with no skills and stats assigned), it would make things easier on me. Playing through the game with the char has some benefits but sometimes I just want someone to say, "Liq, gimme that TC87 and I'll rush you a char to lvl 87"
In addition to the bone spears, other claw viper class monsters use a sort of plague javelin (the infamous bugged vipers which kill most characters almost instantly) and another type of viper uses a weird sort of inferno (it's actually rather beautiful.)
I've seen these guys a number of times in the red portal levels in A5 Hell (Arreat Plateau, etc). I believe they are Salamaders, and their inferno is quite powerful!
As for trading characters, this has always been done *gasp!*, just not publicly in trade forums. Cat's post explains the main reason for this. But...members that know each other, and play alot together develop a level of trust where transactions occur outside these forums. Historically speaking I and many other mods (though I certainly CANNOT speak for Cat or Hrus) didn't get involved in "private" transactions.
I know that for PvP having a "rushed" char just to start assigning points and stats, equip the armor and start dueling may be an advantage.
But the problem is, as Cattleya has appointed, it's trust. Sure, the SP trade forum has gone a little time without any major tainting been done or detected, and now most of the traders know each other and somewhat trust between them, but that's because (at least, in the mayor part) of the "security manners" that the forum has: trader profiles, trader rating and yes, item readouts.
To spot cheated chars would be much more harder than items, and it could cause a major disaster for the SPTF. (For example, if someone wants a TC87, he can create with a hero editor a clvl. 90 char without any assigned points and trade it for a legit item).
I guess the way to trade chars is as it has been done until now: not in public and with member which trust each other.