Experience, Encumberance and Attacks

[Taqwus]

There are also a few melee weapons with an area effect. Ember, the Stone Sword, Sun Slayer, the Sword of Many Colours come to mind, perhaps others. There's also one blade -- Harvest Blade? -- which automatically hits and cripples all units in a square, if memory serves.
But otherwise... load up on Boots of Quickness or the Jade Armor, or use area-effect spells.

[PvK]

Experience also increases strength and 1 per every 2 or 3 stars, IIRC.

Sabre Cherry reported mowing down a frightening number of foes in one turn with some hyper-munchkin unit. I forget the tricks involved.

PvK