Actually, the 'Magical' sunlight would have been because of the same thing.
UV comes from the sun, so for Willow(who is also very intelligent so will be aware of how UV works) wouldn't be creating it because it looked 'purty' but because it would be emitting this harmful radiation.
Not all Suns give off this radiation in this quantity(have a rewatch of the Pylea episode - obviously there is something different about the 'pure' light).
UV waves can be stopped. Interestingly we see in season 5 that W&H have glass windows that allow the natural light of the sun in, but stop the radiation.
Also your flippant comment at the end is pretty stupid.
Ultimately the PTB is Joss, who we know is pretty well versed in Vampiric Lore.
But even in the context the show, your last comment makes no sense.
Why would the PTB's have any say over what weaknesses a Vampire has?
Stop raising valid points! My theory is full of holes now...
You are perfectly correct about the W&H windows, that does suggest it is a physical property like radiation that causes the combustion. I really don't know too much about UV radiation so forgive me for asking some potentially basic questions.
Firstly, we know that it is only
direct sunlight that hurts vampires. We have seen many a Vamp inside with blinds closed or in areas lighted by the sun, but not directly. Does the UV radiation work differently in these situations to visible light? I am aware that I haven't really worded this very well, so I hope you get what I mean. It is just light of a different frequency, correct?
Secondly, are you saying that a certain quantity of UV radiation is damaging to a Vampire? Like how we get sunburn, they get
sunburn? I haven't seen the episode you referred to, by the way, but I googled it and the Wiki entry for Pylea stated that their two suns' light doesn't hurt Vampires. They emit less UV, right?
Thirdly, we have sunbeds. These emulate the natural UV coming from he sun to give a person a suntan. These same natural UV rays are deadly to a vampire, according to all the evidence you have given. Why doesn't Buffy (or more importantly, The Initiative) have a powerful UV lamp like this? I realise that this would be far too easy a way out that would seriously cripple the show, but what I want to know is: is there an actual Buffyverse (or Jossverse, or Normal....verse) reason?
Sorry for the barrage of questions, I just want to understand your reasoning. It seems better than mine at the moment.
Also, about the PTB thing, I just gathered from the many comments about The First and the PTB balancng things that when The Old Ones were banished and The First ensuered Evil lived on in demonic form via Vampires, the PTB balanced this with weaknesses. Or is that too much interference from the PTB? Anyway, I realise reading it back that it sounded way too agressive and way too much like I was stating fact rather than opinion. Sorry about that.