It’s the only weapon without it. All the other offhands/mainhands/twohanders have some life force generation on it.
Couple of ideas would be that Dagger 4 could generate life force based on how many conditions it transfers. 2% per condi wouldn’t be all that OP. Dagger 5 could get a strait up 2% per target hit, or dagger 4.
Even with the fantastic scepter change, I still feel starved for life force when I go scepter/dagger.