Where to get Blast

Where can i get mythril scale gaiters? do they have them at any stores? are they craft-only? i checked giran already.

They drop from mobs, but only the rate from two raid bosses is better than 1 in 6000; Captain of Queen's Royal Guards, 7%, and Turek Mercenary Captain, 15%.

The best place to buy these is to find them in a private store, Dion or Giran.

If you wish to craft them, the mats drop from the two Raid Bosses too, as well as from the Crokian Warrior, Porta, Lageos, Noble Ant Leader, the Dimension Invader Martyrs, and the elusive Ragna Orc Overlord.

and the elusive Ragna Orc Overlord

The Ragna Orcs that I have encountered are part of the class transfer quests for the Orc race. They are in a ravine near the Cave Of Trials in Orcland. I have not (and will not) taken the time to verify the Overlord is there, but I can't imagine this mob being anywhere else. If the OP wants to hunt these mobs and try for the drops: port to the Cave of Trials from the GK in Orc Village. Go to bridge below you, not the one that is uphill. Cross over the ravine, go go to your right a bit, and you will see a sort of ramp, or slope, that takes you down to the area where the Ragna Orcs are. At least, that is the way I recall getting there, and I have done the Orc transfer quest twice.