The reason why Navighast will not receive Sacred Sword (Theory)

[Spiritmon]

Spoiler

A slight tangent (click)

But there are Kyurem who literally have a ice hand and dont learn Ice Punch and a gastly who dont have arms learn Ice Punch...the irony of the pokemon world I guess.

That isn't irony, it's just a strange coincidence. Additionally, I believe the reason Kyurem has no access to Ice Punch is that sometimes, the Pokémon World does make sense. 

For instance, look at its design:

Notice how weak and spindly its arms look. (IMPORTANT NOTE: Those attachments on its back are not hands, but wings. This explains its ability to learn Fly and Steel Wing, and its inability to learn punching moves.) There are a few Pokémon with small arms that can't learn punching moves, such as the similarly-built Tyrantrum, but I can't think of many others off the top of my head, besides maybe Quilava and Flaaffy. Although true that some small-armed Pokémon can learn punching moves, those Pokémon are generally Fighting-types.



Although Black Kyurem does indeed boast strong arms, the fact of the matter is that it's a forme it is able to switch out of, and thus having the move would make no sense (such as Rotom's inability to learn Flamethrower, Ice Beam, Scald, Aerial Ace or Solar Beam, amongst others). Additionally, it is a host/parasite relationship (sort of), and the host Pokémon is Zekrom, who cannot learn Ice Punch.

Gastly, admittedly, is an odd case, despite how its evolutionary line is built. One can only imagine why a big ball o' gas is able to put 'em up, but such is the nature of Pokémon.

On topic, I think the idea of Sacred Sword actually being Sacred is definitely a very neat analysis and explains why something like Bisharp doesn't learn Sacred Sword as it's generally a foul and nasty Pokémon, though why it isn't given to Gallade (hugely a trainer-protector and a very courteous and affectionate Pokémon) is anybody's guess.

Ah now that make sense. Well you are right about Kyurem. I forgot the detail about Kyurem have tiny arms. It would be indeed dificult to him use a Ice with such tiny arms to hit anything, witch is make sense. And even fusing with any of his forms, Kyurem cant learn that move since Zekrom and Reshiram both of them are Dragons with the additional type of Eletric and Fire. About Ghastly be able to use that move, I cant really say for certain since he doesnt have arms to begin with it. It would be the same situation about Arbok be able to use Sucker Punch. I imagine Ghastly using the gasses of his body and his ecto plasmatic body to form some sort of punch, then using the gas to freeze the punch. And maybe Arbok have something similar ability about him using dark energy and make some sort of punch made of shadows or something? Crazy? Yes, but lets consider the pokemon world its a fictional thing so some things its in the peak of impossible.

Thanks. I try to make such conection with Sacred Sword and the mean of holy and the conection of noble pokemon. About Gallade not able to learn such move...honestly I cant imagine the reason behid that. One of my ideas it would be perhaps of his origins as a Fairy Pokemon maybe, since in the mithology Fairies is sometimes mischief and naugh creatures. And even when he evolved to a noble knight pokemon and lost his Psychic/Fairy to become Psychic/Fighting he still have a little of his old nature as a Fairy sometimes. At least thats is the mostly close reason to that. Or perhaps the Pokemon Company simple forgot to add that move for Gallade or simple ignore for Competitive reasons. Imagine a Mega Pokemon with a STAB move with a base power of 90 with the ability to ignore any defence AND evade changes. And the STAB increase the base power of a move to 1,5 or 50%. In other words:

Sacred Sword STAB power: 

Base Power (90) X STAB (1,5) = 135

Now imagine that level of strengh increasing via Mega Evolution, with his already high fisic attack who is already 125, with a high attack and when mega evolved that number is increased to 165. Its 50 more points in Attack. And imagine if he was already buff with buff moves like Bulk Up and increasing his status. Even I fearing that mathematic. Its indeed something to fear.