Variant of the Knapsack Problem
If you set both the values and the weights of each item corresponding to the lowest four levels to $0$, this problem is exactly the standard knapsack problem, so it is no easier than the standard knapsack problem, i.e. it is NP-hard.

You can use the dynamic programming algorithm for the standard knapsack problem to solve this problem, except that you should consider six cases instead of two: the item is not chosen, or its level $a,b,c,d$ or $e$ is chosen, then take the maximum value. The complexity is $O(nmW)$ where $m$ is the number of levels.