I believe the wording of the Klar, despite being listed under weapons, is that it's the equivalent of a light shield with armor spikes. The rules for armor spikes on shields and armor, are that the enchantments are separate. Enchanting a shield will raise it's shield bonus to AC, but not the attack or damage bonus when bashing with it or using the spikes.
I believe the rules are the same here. You pay separately to increase the attack and damage bonus or the AC bonus.
It would cost 3,000 gp (2,000 for a +1 weapon and 1,000 for a +1 shield) + the cost of a masterwork klar in order to have a +1 klar that gave a +1 bonus to both attack and damage and to AC.
A +2 klar that applied to both attack, damage, and AC would be 8,000 (+2 weapon enhancement) + 4,000 (+2 AC enhancement) + cost of masterwork klar.
If you're creating or enchanting one, you don't have to do the full +2 bonus to both at the same time. You could just add a +1 to attack and damage to your masterwork klar, pay for that (2,000 gp/2) and later add the +1 AC. Later, you could pay the difference when increasing the bonus to either as per the normal rules.
