Lae'zel - 12 Battlemaster
The polearm master thing is nice if you find a polearm *better* than
that sword that only Githyanki can use [properly]. I haven't. And, frankly, not any other weapon, either. Sure, staffs that give benefits or a fun hand crossbow; but not a good melee weapon. if you want her to be lore-freindly, she's going to swing a sword. It's what Githyanki warriors do.
So what I did is, also 12 Battlemaster [11 so far, but it'll be 12]
2x ASI to get STR at 20
Sentinel
Savage Attacker
I took.. Don't recall the name. BUt one of her maneuvers give advantage and adds the superiority dice to damage. That's for that time she's only fighting one guy at a time.
That sword also has a special attack with advantage and chance to stun, giving more advantage in consecutive hits.
She also has gauntlets.. I think from the Gobbo base, that give advantage when surrounded by two or more. That's *all* the time. So, Lae'zel has advantange *always*, and with her 20 STR she pretty much only misses on a 1, and with the Savage Attacker she always hits *hard*, too. Sentinel and Riposte ensure her reactions are almost always used.
For the big mobs, I pair her with Jaheira-the-Oath-of-The-ANcients-Paladin. Now she has Bash, potentially knocking dudes down as her reaction. This is *awesome*, because her AC is slightly lower than Lae'zels. So enemies tend to target her first, get knocked down and hit on the head by Lae'zel.
My Lae'zel ahs become *so* godsdamned effective, that I now use Gale to just fling enemies in her range with telekinesis.