Below are the Exploits available to the Fighter. If an Exploit has a prerequisite, like a minimum Ability Score or level, you can learn it at the same time you meet the prerequisites.
1st-Degree Exploits
Exploits of the 1st-degree are minor techniques slightly more complicated than swinging a weapon. They can be learned by Fighters with modest training and have no level prerequisite.
2nd-Degree Exploits
Exploits of the 2nd-degree represent the peak of martial skill achievable by warriors without dedicated training. These can be learned by any Fighter of 5th level or higher.
3rd-Degree Exploits
Exploits of the 3rd-degree are only mastered by elite warriors who dedicate their lives to training. They can only be learned by Fighters of 9th level and higher. Each 3rd-degree Exploit you know can only be used once per short or long rest.
4th-Degree Exploits
Exploits of the 4th-degree are only able to be mastered by the most elite warriors in a kingdom. These can only be learned by Fighters of 13th level and higher. Each 4th-degree Exploit you know can only be used once per short or long rest.
5th-Degree Exploits
Exploits of the 5th-degree are techniques and skills that rival heroes of legend. These can only be learned by Fighters of 17th level and higher, and each 5th-degree Exploit you know can only be used once per long rest.