I feel like disconnecting the mark system from the F1 and having it be applied by, I don't know, malicious stealth attacks vs your primary target let's say would alleviate a lot of the problems I've run into when playing Deadeye pretty much anywhere. Your entire rotation relying on being able to use F1 when you need to is absurd.

That, or making it a mode you toggle in and out of. You mark a target, and that target remains marked until you say stop/die/move too far away/etc. When you've got something marked you can use the F2 essence steal which just recharge after use like a single charge mantra instead of requiring you to keep using the F1 to create one.

Idk, just spitballing here because target marking sucks.