Another idea is that it takes MAX powerlevel, but takes from both your max and current. So you could imbue 5% max PL, but it would also take 5% max from your current (adjust numbers to be balanced). Which would give it the opposite effect, where it’s more of a powerful card when your current PL has dropped low enough where the weapon would do more than a Ki attack based on current PL.
That might also fit better with weapons being more of a flat number/power (it would make the power changes less variable within your own power range).
But still downside because it still subtracts that PL you imbued (it could be that it costs more current PL than the PL put into the attack, or less, or whatever is more balanced. Putting in 5% max could take 7.5%, 10%, 2.5%, whatever works better)
So if you had a Ki attack that did 10% current, you have 100,000 PL, you can imbue your weapon with 5% max PL, when you fall below 50,000 PL the weapon would do the same (plus flat) as the 10% Ki attack (with higher or lower costs depending what you decide), but might cost more than the Ki attack and still not be viable to use until 40%, 30%, whatever
Max PL for the weapon damage and a higher Current PL for the usage might be interesting… Maybe like 1:3. 15,000/100,000 PL you’d charge a weapon for 5% max and it’d cost 15% current, so it would add 5,000 damage and take away 2,250, but at 50,000/100,000 it would add 5,000 and take away 7,500. At full PL, 100,000/100,000 it would still add 5,000 but take away 15,000. Not sure, just a thought.
This would make humans SUPER dangerous at really low current PLs compared to max, so you’d have to want that.
Just some random thoughts I had talking to Mado, hope I compiled them in a readable way here.
Edit: This would also have the side effect of changing strategy in party/group fights (particularly if there are more players in the future). Humans are utility and party buffers (IMO lean even more into that) and that means strategically it makes sense to focus them first in a fight. An ability like this means if you focus a human, but don’t fully take them out, that they’re still hitting at almost max damage from low current PL.