Weirdly… nobody mentioned Ouch Pouch…
Ouch Pouch Miracle. Every dagger unit can use it, but the highest attack dagger units (I dunno if Gangrel fits here, but Kagero and Sothe definitely do) would be what you’d be looking for with the build. Gets better with pulse support too, so Silvia or Olivia with IP makes it more consistent. Rafiel with IP support would be heavenly, instant miracle is no joke.
Aim to get the miracle as charged as possible and tank the HB units with it or get into vantage range using that miracle if needed. That simple.
If you’re not extremely dead-set on Kronya, I advise you to look at your Kagero and Sothe copies in your barracks and consider them, especially if you’ll be tight on grails for the foreseeable future.
And check this channel called “Luna FE”. He has videos of using Sothe, Kagero, and Matthew (Spy’s Dagger with Heavy Blade, but similar Miracle charging principle)
Study up and git gud, friend.
Also, bow units are a bit less advisable to use for it, they’d only be superior over daggers against flier balls that have declined over the months. If they ever made a return though, they’ll still run into trouble because the flier balls would probably run Ashnard or Smol Minerva with their nullified bow weakness and decent def. If you already have an invested CC archer, it’s probably better to work with that unit.