Oak -> Iron -> Steel -> Diamond -> Master, that's the league progression as far as I can tell. Oak seems to be for anyone who dips below the starting 1500 ELO, Iron is the starting tier, and I don't think there's enough difference in ratings for Steel or Diamond to be really meaningful yet. I'm in Diamond, but it's a fickle thing that can change with a single duel. I suspect once more players start shifting away from 1500 that the tier ranges will be significantly more broad. Right now you can go from Iron to Steel to Diamond with a shift of only 30 ELO.
So far I've only played ranked duels with Phalanx/rapier, and what seems to get me is strong offensive play and dodging. Phalanx has extremely narrow attacks, so a quick dodge (left CTRL+WASD) can move you just far enough to the side to be safe and counter attack. His balanced attacks also leave him very exposed, so they're quite risky. Don't expect to attack him head-on though, because a decent Phalanx player will use his quick, sweeping side attacks in any stance to parry you easily.
Pro tip, rapiers can't hit multiple times with a single attack. Phalanx's second attack in the balanced chain is a twirling thrusty thingy, which is his only forward multihit attack. The only possible reason to use it with a rapier is for a single powerful hit to finish somebody off, because you can only hit one time with the rapier. That means if you don't kill someone with it then you're just standing there like an idiot, twirling your sword around for half a second while your opponent recovers.
FYI, the
Blade Symphony guide is outdated or contradictory in some respects. For example, the description of the defensive maneuver of the scimitar says:
Defensive maneuver: Like the Katana, the Scimitar can block all non-tier 3 attacks by holding the defense button.
The katana was changed to have the feint defensive maneuver. The scimitar blocks like the longsword. There are a few other things, like throws. It says there's no counter to them, but if both players attempt a throw at the same time it cancels them both.
This also entirely false:
performing a side attack does not increment the counter.
It most certainly does. It's one of my favorite tactics as phalanx, because his 3rd string fast attack is a long forward lunge, which I use to close distance quickly and interrupt charge attacks or shuriken throws. I can use two quick side attacks to "prepare" the third string fast attack, readying it for a few seconds.