A sealed scroll is basicly a lock to be put on an equiped item. Basicly, you can't sell, trade, or drop the item that the scroll is used on to prevent unauthorised theft and junking of prized items.
You can lock an item for 1 day, 1 week, or 1 month, it's a good idea to lock anything personalised as hackers can drop them in the middle of nowhere out of spite, or synth them for no reason. It's also a good idea to lock any rare item that's valued above 500k, or any item that has a rare enchant on it such as Vine dexterity helmets, or anything that gives a large number of stats.
So basicly, protect your prized crap before a hacker eventualy gets into Nexon's database and steals everything we own.