Removing durability one unit at a time

I was wondering if it is possible to have a command that would remove one durability from an item each time it ran. The best way I can come up with is a having a huge array of command blocks with:
/replaceitem entity @a slot.hotbar.0 minecraft:shield 1 350,
then /replaceitem entity @a slot.hotbar.0 minecraft:shield 1 349 ect .

Cheers!

Your solution would be the best solution. You can probably write an MCEdit filter to easily place all of those command blocks.

Another solution would be summoning a zombie at the player's location execute <player> ~ ~ ~ summon Zombie. The zombie will hit the player and the shield (or armour, won't work with tools) will take damage. It'll be a good idea to give the player resistance as well using effect <player> resistance <seconds> 255 true (the "true" at the end of the command hides particles).