Okay so I know that this post is three years ago and probrably no one read this anymore, but I still want to express my ideas.
What I think is that what this guy said about the misconceptions is the misconception. The arrows ability isn't that hard to understand. I don't know when did the saying of "requiem grand you what you desire at the moment" came out. From chariot requiem's power discription in the manga and polnareff's word, it's clearly stated that requiem is an energy that gives you power to dominate souls. Polnareff also said that who ever can control the arrow's ability, can control the world. If the saying of "give you what you desire" is true. Then you must be thinking of "I want to rule the world" to make that true. There's also another misconception stated that the arrow must give you soul related powers which in chariot's case is true. However that is not what it is. The arrow actually just give a very op ability to worthy people to become the most powerful person. Dominating soul doesn't mean manipulating souls it means to take over. For example when you dominate the world you don't actually control everyone's mind and soul but everyone have to obey you.
GER's power is being able to control "truth". Which both power it had shown is related to that by first: reversing anyone's attack to ger to "zero"by eliminating the truth of you attacking ger and second: give you a looping death by making the fact that you can't arrive the truth of your death.
Chariots requiem's ability is become the shadow of everyone's soul. Which means it can freely manipulate anyone's soul and reversing all your attack. That's why it swaps soul, turn you into monstrous creature, can enhance and control your stand and put you into sleep. It also shows a little space control ability (when sex pistol came out of the piller behind mista, throw the stone at giorno from his back after giorno throw the stone at the arrow instead of just reversing it, and it's broken arm just came out of the lamp post when mista climb on it to save turtle polnareff) and also have the power to regenerate.
I think the whole "give you what you desire at the moment" is just a coincidence given the fact that giorno happens to have an ability that is in reverse of kc and chariot have the ability to get the arrow away from diavolo. But that's just chariot becoming a guarding stand due to polnareff's death. Giorno's ability is due to araki wants to give diavolo the punishment he deserves which is that diavolo had been skipping process and just going the the result and so the ending of him is to never arrive any end.
The power of requiem stand granted by the stand is always the same and it won't change considering that chariot is same the first and second time. However every stand will have different op abilities of course.