By raw stats, the Amphis has an amazingly high base damage, and one of the fastest melee attack speeds in the game, as well as a decent reach, large AOE, and multiple target sweeps. This is looking to be one of the best melee weapons in the game for lower mastery level players.
Heck, best melee weapon regardless of mastery rank, just for its ability to copter, insta-stun jump attack, relative ease of acquiring clashing forest and for electric being a great base for both corrosive and magnetic.
Aaaaand that would be a big mistake. Amphis still has higher damage, higher attack speed and a polarity. In addition to that, none of the polearm stances really shines, while staves got 2 very useful stances,and also both pretty easy to acquire.
Right now the regular Orthos is one of the crappiest Heavy melee weapons.