1) At the start of the fight quickly snipe Fyrus.
2) Grab either of the chains and try to walk directly away from Fyrus.
3) Roll-stab Fyrus.
4) Stand near where one of the chains will be after he reingites and snipe him again.
5) Repeat for three hits, roll-stab is faster than ending blow from behind due to having to wait for Link to land after his backflip.
Pulling Fyrus' right foot to knock him down is slightly faster than the left foot.
All the pots around the boss room alternate between heart drops and arrow drops, if you wish you can collect arrows after the second roll-stab to have the maximum number of arrows leaving the fight (29 Arrows). You could refill hearts after Roll-stab one if you are not planning on getting the heart container.
If you do not have Master Sword then a Roll-stab doesn't deal enough damage in one hit, it is recommended to instead do a Jump Attack into a Spin Attack