WARNING: untested and I just got in from an after work meetup that involved a few beers..
Your logic is heavily flawed. If i have never turned in a single item, thus no quest global yet, i automatically get the item at half power. Additionally once I start turning in items it will go up in 10% increments from 0%. Also, there is no limit to how high the item will scale past 100%. Someone could easily exploit this to make the item much much more powerful.
Finally, you have more { than } so the script is in error and will never compile.
Code:
sub EVENT_SCALE_CALC {
if (defined($qglobals{epic_scale})) {
my $scale = $qglobals{epic_scale} / 10;
if ($scale > 1) {
$scale = 1;
$questitem->SetScale($qglobals{$scale});
} else {
#I honestly don't know enough baout this section of code to
#know it this is required or not to zero out the item.
$questitem->SetScale(0);
}
}