Ice staff never can be a good main tanking weapon unless ZOS would like to revamp those active and passive skills , maybe better create a new skill line for magical tanking weapon ?
Back bar is still OK at this moment ...
Great ideas all around, would definitely make frost staff tanking (and frost staff dps, for that matter) more viable.
I would go with option 2 of frost heavy attacks applying minor breach/fracture, as the flat armor reduction could be a bit excessive. It's already very easy to hit max pen values in raids without an additional 1000 armor debuff. Providing another source of minor breach is also a very good idea because this minor debuff is very difficult to come by (power of the light is the only source that immediately comes to mind for me).
As for elemental susceptibility, I like the first option better. The other morph (ele drain) doesn't add additional effects for the type of staff, so I don't see why this one should. Imo, elemental susceptibility doesn't even need to be attached to a taunt, as this would render inner rage/beast useless. But one morph should definitely provide both major breach and major fracture, at the cost of magicka steal. Keep the cost free, but remove the taunt and let it grant both breach and fracture.
+1
Edit: necro but just saw this thread for the first time today, as it was linked in the comment of another similar thread.