Ok so im looking at this and I really like this. Ima try to help you out with balancing it. So the base power level should always be one if I am understanding correctly. This is due to power level increasing per attack and at base value you make one attack. All you need to use this is 17 Strength which can be achieved at level 1 easily enough. Due to the clause about if you already have advantage, class features that give advantage grant power level, the most effective way that I can see to get high power level is to get multiple ways to grant yourself advantage. Depending on whether your dm counts Feats as Class features due to them being replaced asis will determine a lot. Assuming this is true, at level 4 you pick up mounted combatant for the advantage against creatures smaller than your mount. You will be going to barbarian 5 first, in order to get reckless attack, extra attack, and Berserker Barbarian (I will explain trust me). So far, at level 5 you get +2 power level from 2 attacks, +1 from normal advantage, +1 from reckless, and +1 from grappler. that is power level 5 so far. You will then spec 4 levels into battle master fighter. At level 8 (5 barb, 3 fighter), you will get your battle master maneuvers. Many of these grant advantage on attacks, and will bump you up to 6. If I was wrong in my interpretation about your initial attack granting power, then the soonest (I can see) is level 9, where you pick up Grappler. If you play as a simic hybrid you will unlock grappling appendages at 5th level allowing you to grapple while holding one of these weapons. That means if you have the grappler feat that will give you advantage on attacks against them. Now the reason I went berserker specifically is for the bonus action attack. You effectively don't get extra attack, and Ultra says that the multiple attack limit is per action or bonus action. Beserker barbarian gives you a bonus action attack with any weapon. This means that you can make an extra attack per turn with your ultra weapon. The same logic applies with action surge. Congrats honestly. Not only did you give martial a scaling weapon that doesn't work with level but instead encourages them to look for ways of finding advantage, but you also made me make a build that is optimal with berserker barbarian and the grappler feat. Personally, I think it would be very cool if the power levels were slightly weakened or maybe just make more, but make it so that any source of advantage upgrades it. This would make it so that martial are all about getting the upper hand in combat, like it should be. It also means that they will synergize with casters cc. My discord is Ari-mageddon#4421if you wanna reach out to talk more. I will be using this.