I have never heard of 13th age.
My experience with bards:
BG1:
- They can sing (Singing gives a +1 bonus but he cannot do anything else while singing, like casting or attack. The bless spell of a cleric is better)
- They can wear armor (but they cannot cast when they do and they cannot use mage robes.)
- They can equip almost every weapon (but they cannot specialize and they do not get extra attacks so damage and hit chance are low)
- They can cast spells (Mages can learn more and higher levels. There are no bard specific spells.)
- They get pickpocket for free (OK, my thief can spend his points elswhere.)
This was so depressing that it ruined this class for me.
BG2 was better, but a mage/thief was still better.
In NWN2 they can be very powerful (buffing to immortalety plus curse song), but BG1 disappointed me so much that I used them only to qualify for RDD.
In Pillars of Eternity it is good that they can buff their surrounding while doing something else. But as mentioned before, most fights are over before they can cast anything and all they do is auto attack.
I do not remember playing a bard in another computer game and I never played a PnP RPG.
Prof. Dr. Dr. Mad S. Tist 
