Regarding the energy absorption, it makes sense; we don't need to overcomplicate how the spear interacts with the supernatural portal energy. Even without absorbing it, the Electric Spear is still a powerful 7-C armor-piercing weapon that Rachel can use to deflect or take down incoming physical structures.
However, the comparison to Shovel Knight's situation assumes Rachel is cornered, where she's lost her balance and is falling. But you're missing the most crucial part of the match: the opening.
Charlotte needs to actively slam down on the ground to activate Smelting. In Speed Equalized mode, her attack animation takes time, and her movement speed is exactly the same as Rachel's. At an initial distance of only 10 meters, Rachel won't stand there and watch Charlotte make the slam. And if she falls into the lava, Rachel can use her spear to strike the lava, creating a powerful springboard.
Because their speeds are completely equal and the distance is very short, Rachel can approach Charlotte or prevent her ground attack attempts before the lava spreads across the battlefield. Charlotte cannot safely establish a large-scale environmental hazard while her opponent is right next to her. Rachel prevents the lava problem from happening in the first place by shutting down the system.
Furthermore, Rachel's spear has another ability: the electric spear not only discharges electricity but also generates immense thermal energy, capable of instantly incinerating giant creatures and
even melting sea sand into glass (this requires temperatures above 1600°C). ~~I forgot to add this ability for her due to oversight~~. Although Charlotte has high internal heat resistance, her overheating weakness is triggered by the leakage of internal energy during combat. By forcing Charlotte into a high-intensity close-quarters brawl while relentlessly attacking her with a spear emitting heat energy capable of melting sand into glass, Rachel creates a severe thermal resonance effect. This external heat, combined with the pressure of constant physical impact, will significantly accelerate Charlotte's internal instability, pushing her into a vulnerable and fragile state much sooner than anticipated.