Cleon
Legend
I guess you're right; I haven't played enough at high levels to get to the point where 1d10 Con/1d10 Con soudns "not lethal."
Actually, 1d10/1d10 Con is pretty not lethal to many non-Epic high level characters. Once you get high enough CL for heroes' feast they get an easy means for immunity to poison.
For Epic Characters, a Fort DC 24 poison is pretty easy to save against, and the Perfect Health epic feat provides immunity to it.
I'd be happy with the fix you propose --- it is a plain dagger of venom for anyone else but a keen, wounding, returning dagger of venom with the Wolf Lord's DC set as above and 1d10 Con/death or maybe 2d10/2d10 Con damage or 1d10/1d10 Con drain. I'm also amenable to 6 "poisons" per day.
So which poison damage do you prefer?
With that fix, do we still want all of keen, wounding, returning?
I'd keep the keen wounding returning bit. I'd also be OK giving some of those qualities to the dagger when wielded by "anyone else".
Keen wounding returning is worth a +4 bonus. The "venom" quality of a normal dagger of venom appears to be worth +1 or +6000 gp (since it's a +1 dagger with the price of a +2 magical weapon), but the extra uses and potency ought to increase that. Hmm, a nine lives stealer sword has a DC 20 save or die effect and is worth +15000 gp more than its base weapon (a +2 longsword), which might give some guidance.
Hmm, we should also decide what magical plus to give the dagger. The other Animal Lords have weapons with total boni of +8 (one weapon) or +7 (two weapons), suggesting it should be a +3 dagger. Or we could make it a +1 weapon like a normal dagger of venom and add another +2 in qualities - I'd fancy ghost touch and seeking, to the wolf's fang can easily bite incorporeal or concealed opponents.