Restrictions for Skill Inheritance (Source from Gamepress)
Prerequisite skills must be inherited to gain access to the final level of that skill. For example, if you wanted to transfer Life and Death 3, you would need transfer Life and Death 1 and Life and Death 2 as well.
Inherited weapons must match the hero's weapon type.
Dragon breath attacks can be inherited to dragons of different colours. For example, Tiki (Y) can inherit Dark Breath+ from Corrin (F)
Unique weapons such as Falchion and Raijinto cannot be inherited.
Unique skills such as Close Counter and Distant Counter can be inherited.
Dance and Sing cannot be inherited.
"Goad" and "Ward" skills can only be transferred to units of the same class. For example, Hone Cavalry can only be inherited by other Cavalry units.
Knock Back and Drag Back can't be transferred to ranged units.
Lancebreaker can't be transferred to sword units.
Wary Fighter can only be inherited by armored units.
For more organized skill-list, you can find it here. http://feheroes.wiki/Passives