Well, I was actually thinking of MORE than one bone warrior at a time.
This is
MUCH easier than fighting your dopple because:
-No skills
-Less armor
-Decomposes
Besides, with
Verata's Gaze you can steal one instead of fighting it...
Seems fair to me, although it would make more sense to make it cost 30 energy, even though 30 is an illegal energy cost in Guild Wars, at least for now. This is because when the amount of energy it takes is stored there are only the possibilities of:
-5 energy
-10 energy
-15 energy
-25 energy
This means that it takes only 2 bits, instead of 5...
Still, the lifespan is no problem. All bone things accelerate their decomposition at the same rate, although I never sat there and figured it out :P
Eventually, they will have 25 health degen, and you wont keep them alive much after that....
Also, there is
NO way to make it so you can only have one at once, unless it is a pet similar to that of a ranger, which would be cool but would give necros even more power (they are already superior in my eyes

).
This addition of power would then be nerfed
blah blah blah blah.... Its not like there is going to be a big advantage for more than a couple weeks

.
Also, you can't do the skills because then they would literally be new members of the group, which is way too much for something that can be summoned at will.
Note: I've seen people in HoH and GvG use teams where EVERYONE uses pets, and they have a bit of an advantage. The only disadvantage is that most build require at least 7 if not all 8 skills to function.
The AI for the skills would also be subject to confusion....
Still, they should do it anyway