Am I missing something?
7200 is very low to be coming into the boss fight with, and the only way I could get that low is by finishing in the wrong gear. Keep in mind that most of your RPM for the blade battles comes from the RPM at the end of the race, i.e. how high the tachometer dial was, with gear and time bonuses being minor in comparison.
Stage 3 is a little counter-intuitive in that you should almost always be finishing in 4th gear instead of 5th gear, getting your last upshift in after the bridge and just before the final corner. This is because the final straight is too short to build up enough RPM in fifth gear, you might get more gear bonus (1600 in 4th VS 2500 in 5th), but you're throwing away an easy redline in 4th (7000+ RPM) for a very mediocre finish in 5th (~4000 RPM).
The blade fights felt really unfair because it seemed like any input I made with my cursor weren't responsive enough, and any dashing movements would constantly overshoot.
The blades will follow their inertia and the contour of the bowl more than anything else, any non-dash movements will make relatively minor differences. And, unless you're attacking, a dash is best used perpendicular to the bowl's radius to be able to pick up speed and orbit around the bowl. If you dash directly towards or away from the centre, you're either going to overshoot or just rock back and forth as an easy target. And for the record, the NPCs use the exact same movement behaviour and physics with a virtual cursor, so you're on an even playing field in that regard.
I really wanted to finish the game, but I couldn't.
Let me know if you manage to finish the game, or at least beat Titan Blade, after reading this!!