With the recently Sure strike change, Knight Commander's Sabre is imo overtuned. With unrestricted spell like Bless weapon, Corrupted weapon, this weapon becomes a monster.
A masterly scimitar does 1d6+6. A corrupted Knight Commander's Sabre does 2d3+6+2, 2d4 massive crits, plus bonus like +2 CHA and +5 Sure strike.
My proposal is remove the extra 2 blugn damage, reduce CHA bonus by 1, that will make it in same power level as other 18-20 weapons.