Remove memoization from #handle

At the moment the #handle method on the different objects will memoize the Handle object, which means that if #handle has been called once, the Handle object will stay the same until it is explicitly set or cleared. This means that the synchronization level of the Handle objects depends on where the #handle method is being called, which is not optimal. Another thing is that #handle is a get'er method and should therefore not mutate its object.

With this PR, the handle object is not memoized anymore, such that the handle object is always synchronized until the handle is explicitly set.