Alright, for Ferdiad. His personal skills alone make him very powerful, with the ability to use 18 original runes to buff himself, use damaging spells against the enemy, or whatever support he needs, combined with battle continuation and warrior of the ford, he would be very hard to take down.

Also, there is quite a lot of rank ups.

The noble phantasm thus serve to make him rather over powered. Trom is borderline acceptable, but that static rank up is kinda iffy. Does it simply rank up his strength to A, or does it add a + to the rank? 

Duel of the desperate seems to be simply a souped up Ath n Gabla but the problem I'm seeing here is the rank up and the defense piercing. The rank up combined with the Warrior of the Ford, using the 18 runes to buff yourself plus the sword's rank up gives a very nasty combination that allows you to steamroll through most conventional heroes. The rank down is alright imo. The defence piercing is highly unnecessary considering the skill of Ferdiad as a warrior.

The skin is mostly alright except for that it reflects damage back to the attacker. 75% of damage reflected back is very high. This alone would allow him to simply facetank most everything and kill them while they kill themselves. Combined with the others, he could very much end the war by himself in the first day. Also, I doubt most people know about conceptual weapons or know about the realm of authorities.lol

The character concept is quite good actually, but all the rank ups are very iffy, especially since Warrior of the Ford plus his runes would already make him powerful in close combat. He is more suited to be in a game as an antagonist, where the protagonist at least has the story to back them up and perhaps some deus ex machina to be able to defeat him. My suggestion would be to tone Ferdiad down, especially all those rank up, fix up that Skin some, and leave warrior of the ford.