How to drive home the dangers of the Sight?

[Taran]

It's not just BAD things you see, it can be things that change you as a person.
You run across an Angel, or a Fae Queen, or one of those things that hangs out where normal eyes can't see.
or heck, maybe they catch their reflection in the mirror.

This.  This is awesome.  He opens his sight and there's someone's guardian angel sitting there... If it's a murder, or just any random death then maybe The Grim Reaper is standing there collecting the victims soul...

Compel him to open his Sight at a car accident while all the Emergency people are there trying to rescue people from the wreckage. 

[Sanctaphrax]

Why not just talk to him, tell him The Sight is a big deal, and have his character take an Aspect that relates to frequent use of The Sight?

Failing that, bear in mind that the most dangerous thing about The Sight is that you don't know how dangerous it'll be until you use it.

"The crime scene would only be difficulty 4 normally, but the invisible Outsider sitting in it makes it difficulty 10. On the upside, it now won't be as surprising when the Outsider tries to eat you."

[fantazero]

TO OP: you are making him roll to CLOSE his sight, correct?

[Taran]

The role to resist and the roll to close the Sight are the same role.  If you fail you are unable to close it and must spend the next exchange trying to resist/close it again.

But the Lore roll is an "assesment" action and if that fails, you get no information and therefore could keep your Sight open another exchange to attempt another assessment action.  The Lore roll is the same difficulty as the intensity.  So an intensity 5 vision is a Lore 5 to discover anything useful.  With that in mind, if his Lore is lower than his discipline, he might need to keep his Sight open for multiple rounds, giving him more opportunities to fail his discipline.

EDIT:  I'd also like to add that, according to YS, looking at Murphy - because she's a main character, central to the plot etc... - was a +4 Great difficulty to resist.  Seeing the cop wracked by the psychic vine was +3.

It also advises that all visions START at +3.  THis can go up or down depending on whether the wizard focuses on something small (gets less information) or focuses on the larger picture (gets more information).  It doesn't say so, but I imagine the difficulty of the lore roll would go up or down in proportion of how focused the wizard is trying to be.

With that said, if your player has a lower Lore, you can tell him he'll have an easier time deciphering the Sight if he takes in more information.  This is a "by the rules" way of increasing the difficulty to resist.

[PapaD]

Things to remember

1. Things you see with your sight stay with you forever, clear as day, no fading over time - thats something you really want to consider when thinking up difficulties
2. If your player is really using the sight all the time, consider the other characters in your party - in mine, one guy carries a large ornate cross made from the original cross of jesus - this is not a simple think to look away from - i've had one guy open his sight to look at something, and forget to check who was stood in front of him at the time.
3. You can always decide a difficulty based on how troubling you think what is being seen will be to the character - if he's an innocent soul, then murder is likely to be more traumatising than it would be to a hitman.