I’ve been using this weapon since before AoM and I love it and the visuals that the skill it gives the player has. However, I rarely felt like I got a chance to use it with its fairly costly energy cost when I was using Cleave as my main attack. Even with how I am built now with a focus on Cadence I just don’t feel like there is room in my survival rotation to use its ability.
Looking at a different hammer now, the Avenger’s Crusher, it has a similar ability to the Obsidian Juggernaut but with lower damage and is triggered on a chance when you attack. My suggestion is to maybe do something similar for the Obsidian Juggernaut and bring its skill in line with the Avenger’s Crusher. Make the skill an on hit chance trigger and lower the base damage of the skill to help balance that out.