I totally agree with this, I picked up shade a week ago and it has some serious core gameplay issues most of which can be tied to the level of respect you must have for every boss to play it efficiently.
comparing shade to pure fallen, one of the only comparable burst damage classes, shade has to stack up marks, consume them for knives, stack marks again, and then start doing damage (if theres no minions you will have to consume twice btw) you will spend around a full 30 seconds or more just doing prep work on your first li boss only to deal damage comparable to what fallen does right out the gate. Throughout the run youre then forced to sacrifice damage opportunities to instead consume marks to keep up your knives up whereas again fallen just steamrolls through with no setup.
This is not to say fallen is op or anything like that, shade as a class is just too slow and too setup reliant for what its competing with, and demands way too much setup time and respect for the level of damage it puts out.
I think that a good start would be allowing shade to always stack full knives off a single target, allowing the knives to persist after swapping, and then switching them over from a time system to a durability system closer to how ophanims work (minus the natural decay) this would allow them to be preserved in raids and give shade a much needed QoL spike, as now you really only need to stack marks which is way less taxing on time. This system would also allow more skill expression, as players can gage exactly when in a combo they will need to refresh knives instead of doing so just when the timer is low