Working as Designed Tools dealing damage through "half-blocks"

[MagoBR]

Your Terraria Device

Galaxy j6 prime

Mobile OS

Android 10

By hammering some blocks (any type) into a half-block shape, it becomes possible to attack enemies through them, using weapons that shouldn't be able to do this, such as the Copper Broadsword and Spear.

 

[BelinhoBR]

Pretty sure this is a "feature"
All AI can also see you through the block and try to shoot it (if they're a projectile enemy)
Minions that phase through blocks can also attack through half blocks, as their AI can see through half blocks aswell, just like any other AI

 

[Nescre]

Thanks for the report! As this matches the PC version, the behaviour you’ve described is by design.