For those of you who have not figured it out, blue glow on items drops when
the item takes damage. This includes the recent eq damage tune.
However, this is only part of the truth. Blue glow, like yellow glow, lasts a
certain duration even under the most extreme conditions. Go ahead and try it
out, weapon prot a crap dagger and magic missile it 50 times. The glow won't
drop.
The blue glow drops the first hit AFTER the duration has expired. As such, the
new eq damage tune can "remind" an item its blue glow has run out, but it does
not itself make the duration any shorter. If you are worried about your items
taking damage, you will want to keep them protted a little more routinely than
you have been before. Even the crappiest of merchants can keep the glow going
for a 4-hour exp run, and masters can prot them much longer.