General questions about necro
Your questions all have essentially one answer: change to a power/crit build.
Both axe and dagger scale off of power. If you try to use axe or dagger with low power they will suck.
The 25 stack limit is indeed a big problem with group single-targets (bosses, etc.).
By switching to a Power/crit build, your dagger and axe will hit hard, and since you primarily are using direct damage, the stack limits don’t affect you. In addition, your DS Life Blast will hit hard, and you also be able to destroy structures much, much more quickly than a condi build.
It is the sad reality of GW2’s PVE mechanics.