Hliðskjálf (北欧王座 Hokuō Ōza (Furizusukyaruvu), lit. "Nordic Throne"): Named after Odin's throne, it is Ollerus' power to change his life energy and normal magical power into an unexplainable type of power. The power by its nature cannot be described, can't be explained, and can't be comprehended. The Hliðskjálf doesn't have any offensive function normally, but by forcefully using Hliðskjálf as an offensive power makes it even more unexplainable. He uses Hliðskjálf due to the fact that his own mana is too special and can't be used with normal magical powers, even if he applied knowledge of various grimoires. When used offensively, Hliðskjálf takes the form of an invisible spell that blows the enemy backward without Ollerus making any kind of movement or sign. It does equal damage to every part of the body including internal organs. It has no identifiable source. According to Ollerus, this attack cannot be defended against, as the enemy cannot even begin to mount a defense against an attack using an unexplainable power coming from an incomprehensible place while not leaving them a chance to form a countermeasure.
Pretty sure his weapons reduces damage by 50% or so automatically. Add the likes of swordmaster skill and it can go up even higher, that should be enough to at least survive a hit from Ollerus to summon Bahamut.
You mean you need to equip it before the quest? Captain always bring ten weapons to him before he does basically anything, he's already equipped before he fights. Internal organs negates it to an extent, but not to the point that it can negate dura altogether, organs are still 5-B, it's just in the lower spectrum.
Hundreds of millions of attacks that literally just hit the target, deal equal damage to the entire body and distort and break space-time. The attacks don't have travel time, they literally just happen at the target. They spawn at the target.