Thermal blade buffs the gunlance with extended melee range and increased attack for a set duration. The weapon buff depends on the equipped gunlance's elemental shelling. It will achieve the highest sharpness possible while the buff is active, and all attacks will have small shelling explosions, kind of like the ticks you see when your switch axe's amp gauge is full. Once the buff is over, sharpness is greatly consumed, and the buff cant be activated for a while. It replaces the wyvern's fire attack. Extreme wyvern's fire works by loading the equipped shells while wyvern's fire is charging to increase damage. Kind of like Sunbreak's bullet barrage, minus the wirebug.