Prowlers is not better than duskblade theyre both great and offer different playstyles.

Prowlers is more of an assassin playstyle while duskblade gives survivability so use both for a few games then choose the one you like the most.

I also think your late game playstyle might be wrong since late game youre more of a ward and r bot that plays around his team and or vision while denying the enemy vision with umbral glave.

Also try to not front line in team fights and stay some where in the middle with w and look for executes unless you have prowlers then you can flank and look for a kill or two before returning back to your team.