That's a bummer, i was planning on spending my points there.

Hopefully we get an official response.

Mighty seems to be bugged as well...

Seriously this needs a fix.

Wait, someone is confused here. Mighty doesn't increase your weapon damage, it increases your actual physical damage - of the attacks themselves. Try a few light attacks -> put points in -> should increase by whatever %.

Precise Strikes and Piercing and Mighty don't work the way you think they do.

Precise Strikes does not increase critical percentage, it increases the amount of bonus damage when you crit. Normally a crit does 1.5x normal damage. With points in Precise Strikes, it will do 1.55x damage or 1.6x damage or whatever. The tooltip only shows base damage, not critical damage.

Piercing affects how much of your attack that an enemy mitigates with their armor. Your tooltip may say 1000 damage, but you will do less than that based on the enemy's armor. In Update 6, different enemies tend to have different armor. So you might do 980 damage against a fire mage, but only 900 damage against a heavy melee enemy. With points in Piercing, you might instead do 985 and 920 damage, respectively, because you are bypassing some of their armor.

Mighty does not affect the weapon damage stat. It affects attacks that do physical damage, which is a particular type of damage, like disease or fire. You will see the damage type listed under the tooltip. For example, Poison Arrow uses Stamina and scales off Max Stamina and Weapon Damage, but it deals Poison Damage. It would not be affected by Mighty. Snipe uses Stamina and scales off Max Stamina and Weapon Damage, but it deals Physical Damage. It would be affected by Mighty. I would expect this to show in tooltip, not character sheet.

I am not saying these stars are definitely working, just that they do not work in quite the way you think and you need to look in different places to determine if they are effective.