You can't enchant the swords with the enchantment IMPALING. And it's also not possible to enchant the trident using the UNBREAKING and MENDING enchantments
Note: Commands to enchant do not work
MCPE-31884
Swords and tridents can not be enchanted with certain types of Enchantments
Resolved
Duplicate
0
(Unassigned)
Unconfirmed
Phone - Android - Samsung Galaxy S5
Android 5.1
enchantments, impaling, mending, swords, trident, unbreaking
1.2.14.2, 1.2.14.3
Retrieved
1. Are you sire Impaling can be applied to a sword
2. Impaling only works on 'aquatic' mobs (fish, guardians, squid...)