A few things of note before watching this video:

1. Rocket boosting upwards just a slight bit earlier may produce a better result than what I show in the video here.

2. A softer jump off the vine right before initating sword slashes on the weak point seems to line Sparkster up better for higher damage.

3. In the video I don't land on the right platform. This is a mistake as landing directly on the right platform doesn't actually prevent damage from being inflicted on the weak point as long as you keep attacking the weak point as you land. Pretty sure this is a glitch that one can take advantage of.