The reviews on Komoot about the Wurzen Pass say it all from “Brutally steep” to “Hardest climb I did” to “Once is enough”.
The gradient itself isn´t very brutal, or way more extreme than some other mountain passes. It might be a combination of the crapy asphalt at the beginning of the climb, then the steep gradient in the middle and the fact that this steep part has no single curve. This means that you don´t get any second, to recover physically and -most important- mentally.
It is rewarding though: once you are on top, the part between the end of the climb and before your descend into Slovenia is a nice area.
And next to that, the climb is also a ´nice´ shortcut if you want to go from Villach/Austria to the Vrsic-pass.
From the Slovenian side, the Wurzen Pass is relatively easy to cycle. Because the valley on the Slovenian side is quite a few meters higher than the Austrian side, you have way fewer altitude meters to conquer with a more acceptable gradient. Only be careful because the downhill is -of course- very steep.
We don´t organize tours over the Würzen Pass, because it would be simply irresponsible 😉
But the the Cycling Tour that comes dangerously close by the Würzen Pass, is this one: