It’s bad that the developers did not add the ability to describe objects and blocks in Minecraft Pocket Edition. And it’s good that there is such mod as Item Editing Forge (AnAnvilThatCanNameItemsInNewLines).
In order to mod worked, go to settings (global!) Minecraft PE, and activate it. An important point: if you combine with other mods or large maps, be sure to move An Anvil That Can Name Items In New Lines up. And now we take any of the items in Minecraft Bedrock Edition, go to the blacksmith’s table, and in the window that appears, enter the inscription, as is the case with this paper.
The work of the mod is the same when playing on a PC, or from a pocket device. You can change the description of the weapon in MCPE.
Or even a spawn egg, or a tag.
How it works for NPCs and mobs.
Have a good game!