It should be very similar to Geats' empowerment. The big difference is that Blade has a set limit to his AP/Dura while Geats is vaguely broad. Usually he'd take a while before his Fusion Rates rise up to that level, but the speed at which he reaches that level is boosted dramatically by being determined to win, especially in extremely worse case scenarios For example, he got stomped by one powerful undead who's as powerful as his King Form (3x Ace Blade AP) but during their final fight, the latter took away all his Rouse Cards (the cards used for his techniques and stuff in his rider form), prompting him to reassert his beliefs on fighting for people that can't, and thus his Fusion Rates rise up to defeat the undead.
TLDR: Being stomped and/or being very determined to win.
Unsure by the exact number of hits, but even she should give him some trouble. Even the lowest level of undead can be a danger for the Kamen Riders of that series. Seeing as Kokken looks 5, Kenzaki should go easier on her too. And the range is ample enough to land enough hits on him to defeat Blade. Most of his kit works best when up close and personal, so he's more dangerous for her when she gets into his range. Also he has piss poor LS.
Actually, Blade should have Superhuman movement speed (17.54m/s to be exact) since the speed given in the profile is just for his combat/reaction speed. Riding his motorcycle would net him 340km/h, but it leaves him more open to her attacks in comparison to going by foot (sure he can swerve here and there, but he should be hit more often). Mach Jaguar (his speed amp) boosts both his and his motorcycle speed by an undefined amount, though there is clearly a noticeable boost. At least it's not as powerful as Geats' Boost Buckle that not only amps Geats' speed by several times when used but can also further amp him by that same multiplier a second time (x9 speed, AP and Dura is balls) That's why that's completely restricted for Geats, speed equal or not.
EDIT: Also this.