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Does this mean Quicksilvers become an "aura" or "buff" for allies/yourself? Is it affected by aura effect or things that affect buffs?
No.
This is basically the same mechanic as Umbilicus Immortalis - when you use a quicksilver flask, that flask's effect is applied to nearby allies (as well as to you, since this item doesn't prevent flasks applying to you). The effect on each of them will continue to apply until it expires, they don't have to stay close to you.