James McMurray said:
True, but that does not grant them saves against effects that normally do not allow saving throws. Blade Barrier does not grant a save except when first cast, therefore anything subject to its damage will take that damage when it enters the area.
DMG pg. 176.
Damaging Magic items
Magic items should always get a saving throw against spells that might deal damage to them-even against attacks from which a mundane item would normally get no chance to save.