I can see how this will probably all play out but I could be wrong too.
grace/cicada is from the future in nora's timeline, she never had a dagger like her uncles to begin with.
Thawne is always steps ahead, he's calculated and makes moves/decisions like pieces on a chess board. My guess is thawne through his experience with time travel stole the dagger from another timeline and strapped it to his chest, hoping that if he could convince nora to convince her dad to use his plan that when they blasted the dagger in flash's timeline it affected the one on thawnes chest, which ultimately will likely send the dagger/thawne into another timeline or earth, therefore thawne escaping extinction/prison.
I assume once he's out of the prison he'd get his speed back and be fine.....so his plan all along was to manipulate nora for his master plan. In some ways thawne does have "feelings" but that doesn't mean he won't manipulate someone to gain trust for another reason, he did it with barry and nora should not be a surprise.
Also seemed like when nora tapped into the negative speedforce she was more powerful speedster, you would think tapping into the positive speedforce would make you more powerful like it did to barry when he stayed in there...when he came back they mentioned how no speedster has ever gone that fast when he saved iris from the samuroid (and I doubt barry was even going the max).
So thawne should be quite abit slower than barry now, simply because in terms of villains and who's the fastest, I rank them like this savitar, zoom, RF, Godspeed, and the Rival....so if barry is faster than savitar than he basically should fairly easily outrun thawne.
The only advantage is if thawne had tachyon enhancements on him then he'd have the extra speed.
I would say RF and zoom are probably around the same with no V9 or tachyon devices, Godspeed in the show couldn't even catch Nora so he's nowhere close to being faster than RF, zoom or any other villain except the Rival, which I put last.
Also as a sidenote godspeeds lightning color being white means absolutely nothing, they said it was because he changed one of the elements in his version of V9 which altered the lightining color, instead of blue like zooms his changed to white....it has no barring on who's the more powerful speedster....though I'd assume a pure source of the speedforce like barry has (at least in the comics) would go without saying who's the more powerful speedster.