Returned random item (weighted) from generic item factory

I've got a problem with my item factory class for a little game I am trying to code at the moment. What I am doing at the moment is the following:

• I've got a List containing all my possible game items of type x (armor, weapon, ...) with base class type Item
• Each item has a rarity from the rarity enum (0 = common, 1 = uncommen, and so on)
• The actual rarity "spawn" percentage is saved in a dictionary containing the rarity and the percentage
• Currently I have a generic method returning new instances of random items:

public IEnumerable<T> GetRandomItem<T>(int count = 1, Rarity maxRarity = Rarity.Common, List<int> ids = null)
  where T : Item
{
  InitializeActualRarities(maxRarity);
  return GetItems<T>().ToList().Where(i => CheckItemConditions(ref i, maxRarity, ids)).Clone().PickRandom(count);
}

• The item(s) returned by the GetRandomItem Method is(are) always a copy of (a) randomly picked object(s) from the item list.

• The InitializeActualRarities method generates percentages for all rarities below max rarity:

    private void InitializeActualRarities(Rarity maxRarity)
    {
      _actualRarityPercentages.Clear();

      var remaining = 100;
      Enum.GetValues(typeof(Rarity)).OfType<Rarity>().Where(r => _staticRarityPercentages[r] >= _staticRarityPercentages[maxRarity]).ToList().ForEach(r =>
      {
        remaining -= _staticRarityPercentages[r];
        _actualRarityPercentages.Add(r, _staticRarityPercentages[r]);
      });

      var key = _actualRarityPercentages.Aggregate((l, r) => l.Value > r.Value ? l : r).Key;
      _actualRarityPercentages[key] += remaining;
    }

At the moment I am obviously not using the actual rarity percentage in my GetRandomItem Method, and that is just what I want to change.

I want adjust the linq in a way to ensure only items to the given max rarity are returned with the rarity percentages from the _actualRarityPercentages dictionary.

Has anybody an idea or some advice on how to solve that kind of task in my coding manner?

Thank you in advance!