Baldur Blade and its drop rate?

[Rongway]

1 item not dropping while the rest does is obviously not random.

You don't seem to understand the concept of randomness.

If there is a 1 out of X probablity of some event happening, there is a (1 - (1/X)) probability that the event does not happen.

Let's assume there is a 1/15 chance of seeing a particular weapon on a given run. Then there is a 14/15 chance that you won't see the weapon on a given run. In two runs, the possible combinations of weapons dropped in run A and run B are 15 * 15, or 225 possible outcomes. In 15 of these outcomes, weapon A is the one you want. In 15 of these outcomes, weapon B is the one you want. Then we have to apply the Inclusion-Exclusion principle, because we're double counting the outcome where both A and B are the weapon you want, so subtract 1. So the probablitiy of seeing the weapon you want after two runs is 29/225. This happens to be (1 - (14/15)^2), the complement of the probability of seeing any weapon but the one you want.

So, if there are fifteen weapons each with an equal probability of dropping, there is a (1 - (14/15)^n) probability that you will see the weapon you want within a given set of n runs.

Now, given a high enough n, this value approaches, but does not reach 100%. And remember what I said earlier: if the probability is not 0% or 100% you cannot claim any guarantees.

Does it suck that you haven't seen the item you want after X runs? Sure. Is something wrong with the system? No. You just don't understand randomness.

Even if the one weapon you wanted had a 99% chance of dropping, there still exists a 1% chance that you will not see it after a given run. After 100 runs, there would be a 99.9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999% chance that you would see the item you want. But this still isn't 100%, and though it would be incredibly unlikely that you didn't see the item you wanted, it would still be possible.