How would you price such a weapon, in terms of overall bonus and cost?
Each on their own:
Keen is a +1 bonus cost
Luck blade is +2 shortsword that gives a +1 luck bonus on saves and 1/day save re-roll
Shortsword of Subtlety is a +1 shortsword that gives a +4 bonus to attack and damage on sneak attacks
Each on their own:
Keen is a +1 bonus cost
Luck blade is +2 shortsword that gives a +1 luck bonus on saves and 1/day save re-roll
Shortsword of Subtlety is a +1 shortsword that gives a +4 bonus to attack and damage on sneak attacks