Corax, I think the sorceress is too badly nerfed (look how many entrants there are...). Any single-tree sorcie will be powerful up to NM, but will struggle mightily in Hell, so any sorceress tree could be allowed, really. At least allow her Teleport, so she can make better use of her merc. Maybe allow one point in Glacial Spike.
Sorry to be a nag, but I am still not completely clear about skills provided by items. You have narrowed it down to any melee skill and those from the unrestricted trees. In your examples, you only list skills from the same character class. How about these situations. Are they allowed?
* Any class using Zeal and Berserk from a 'Passion' weapon? I would think this is OK since they are melee skills, right?
* Non-necros using charges with necromancer curses. Cloak of Shadows or Posion Creeper charges used by other classes than assassins and druids, respectively. Not melee skills, but they are from allowed skill trees.