Is there any feat which will give bonuses on attacks increasing with level like inspire courage?
I'm aware of the bard, archetypes like the evangelist cleric, VMC bard and the skald. Also feat like flag/banner bearer. That's not what I'm looking for.
Anything that would come independent of class would be good. It might even be a chain of several stacking feats.
Doh, forgot to add, no 3rd party please.
The ability you are looking for (and those like it) are often locked into class progressions and the flag/banner bearer is one of the few exceptions. The things related to attack/damage bonus that effect the entire team left over are narrowly focused teamwork feats and are a heavy investment for the party unless you can share the feats with them, which tends to be class/archetype restricted.
ie, You are pretty much out of luck finding what you want without specific classes/archetypes/VMC options.
Buy everyone a potion of heroism.
Actually the DIVINE FIGHTING TECHNIQUE for IOMEDAE gives a +2 sacred bonus to attack/skill/save rolls. If you can get to the advanced prerequisites you can use it as part of a charge and it lasts for 1 minute (read: lasts for the rest of the combat). There may be other deity options for DFT that buff your allies.