Hi, I have been playing DnD since before, well before there were apple computers and back in the 90's while playing 2e DnD a friend of mine developed a version of bladesinging that was all offensive and want to try to make it for the Pathfinder system as a class.
They were highly efficient melee fighters that specialized in a single bladed melee weapon, fighting with 2 of them at the same time, always each were the same weapon. They could increase their speed of attacks immensely in very short bursts a limited number of times per day. Could also double their personal movement.
They were called Doomweavers and were a knockoff of Bladesinging from the 2e Elves book, as Bladesinging skill was turned into an offensive art and used by dark elves.
Bladesong from 2e DnD was as follows
Bladesong initially did cost 2 proficiency slots
1. They may gain a +1 bonus to their AC or, if they wish to spend an extra slot, may boost this bonus to +2 to their AC. That is the highest bonus those who choose bladesinging as an additional skill can attain. or
2. They may gain a +1 to hit, or if they wish to spend an additional slot, may boost this to +2 to attack. As with the AC bonus, +2 is the best they can hope for, or
3. They may attack and parry in that same round, without wasting any additional attacks
The Doomweaver version was as follows
1. They may gain a +1 bonus to their Dmg or, if they wish to spend an extra slot, may boost this bonus to +2 to their Dmg. That is the highest bonus those who choose Doomweaving as an additional skill can attain. or
2. They may gain a +1 to hit, or if they wish to spend an additional slot, may boost this to +2 to attack. As with the AC bonus, +2 is the best they can hope for, or
3. They may double their attacks in that same round, up to a total of 3x per day.