You seem to have a lot of misinformation or are making a lot of assumptions.
First of all, double attack and compendium have 0 impact in the amount of procs someone could possibly get from this buff. And haste and dualwield would make up a negligible amount of difference, basically unparsable amounts.
This spell as it is scales very little based on anything weapon related other than the fact that having better weapons means you will do more damage during the period of time you are fishing for procs. This will remain true even after it is changed to last until x amount of procs have happened. Don't confuse this with someone at a higher tier getting "more" from this spell because that's simply not true. In fact the immediate impact of getting this spell will be larger than the benefits you get through out the tier, which is basically true for every spell in the game.
The end goal of this spell is to be a small increase in dmg from the ranger overall actually, but it will require more engagement on the part of the players compared to the current Ranger playstyle, which isn't a bad thing considering the current state of Rangers. You may disagree with this statement, but right now Ranger is easily the most passive class in the game to play at near maximum efficiency, and due to the range of bows it is an incredibly safe option too for many fights.
No one is going to become "OP" because of this spell, I don't even know how you even came to this conclusion honestly.
Lastly, you seem to have some kind of impression that Rangers are meant to be only a ranged class, which is just not true. They are surely the best ranged class in the game and that is not going to change, but they were never meant to be the "archer" as you put it. Rangers have some of the best melee capabilities in the game, second only to monk. They have more AA abilities that only work for melee than they do for ranged, and the last tome for rangers (which has yet to be implemented I admit), has intentions of being melee focused. Honestly the whole RANGEr thing is pretty trying and is mostly a stupid play on words. I want to make it clear that rangers will still be spending most of their time at range but that doesn't mean it has to be always, or that they should not be able to hold their own to some extent in melee range.