I really don’t. The Relic sword is not the slower weapon of zealot arsenal. It staggers easily with the special and deal insane damages. Even unpowered, you can deal with hordes (perso I use to not use the special against horde once I reach a 50% heat to keep it available when 20 dreg ragers will come).
This is even the idea behind the poll I created: [POLLS] Discussion around balancing the game
In it 25% have picked combat axe, 17% chainsword, 13% Heavy sword, 6% pick axes and greatsword, 5% bully club and relic blade.
But I agree about the general appreciation toward one weapon as a reference.
But here the OP wanted a “scientifically” and "objective"method. And if you want to identify what is overpowered, so above the other weapons, the best cue is to check at what players pick for their games.