Why is Aid a 2nd level spell?

[Victim]

You could say that Aid is 2nd level because effectively you could say that the character is gaining an extra HD (potentially you could even argue 2 HD in the case of D4 HD classes). Tac onto that the +Level which will be at least +3. A 3rd level Cleric casting it on themselve could almost be considered 4HD (even better cause the BAB from 3rd to 4th with the Avg. BAB is doesnt change). Thought of in terms of a extra HD its power as a 2nd level spell seems more recognizable (at least to me).

As someone said earlier. put it on your wizard or sorcerer and it could right well save them from getting killed, expecialy at low levels. Wizards and Sorcerers are usually under 20 HP on the high end at 3rd level (heck, pending their CON score they might have 15). Where-as the rest of the party will concievably have as much as twice as many. The benefit of having an extra 7-8 HP can be the ability to survive an extra attack allowing them to step back and blast whoever just hit them or at least flee.

BaB bonus increases from 3rd to 4th level for every character class.

False Life blows Aid away short and long term for the purpose of protecting low HP casters. More HP and more duration. Also, many arcane casters will waste the morale bonus to attacks. The morale bonus also doesn't stack with other spells. Aid is probably most useful in a small group. Bless won't affect a bunch of people, so the difference between buffing the group and one guy isn't so significant, and with fewer characters to receive attacks, the temp HP should come into play.

But as short duration buff, Aid will most likely be cast either at the beginning of combat or in whatever ambush rounds the party can scrape up. In combat, it's not a very effective action. Other buffs are more effective on either offense or defense. Aid is like a spell for people who can't think of a better one to prepare or cast; it will never be very good, but it won't be useless either.