Because this is kind of AU (since he went to Durmstrang not Hogwarts) or headcanon anyway... XD
House: Ravenclaw (although the hat did stall - he could also have gone into Gryffindor or Slytherin but intelligence managed to just pip reckless courage and ambition. I've done a ton of sorting quizzes for him in the past and most of the time he gets Ravenclaw, though it usually is borderline with the 2 others. He's just never a Hufflepuff.)
Blood: Pureblood, but he doesn't really care about such things. Wand: (Old headcanon, not Pottermore checked and not made by Ollivander) Oak, sturdy, 11 1/2 inches, dragon heartstring
Grindelwald
House: Ravenclaw (although the hat did stall - he could also have gone into Gryffindor or Slytherin but intelligence managed to just pip reckless courage and ambition. I've done a ton of sorting quizzes for him in the past and most of the time he gets Ravenclaw, though it usually is borderline with the 2 others. He's just never a Hufflepuff.)
e.g. Two actual results from online quizzes:
Gryffindor - 13
Slytherin - 13
Ravenclaw - 10
Hufflepuff - 4
And:
52% Ravenclaw
36% Slytherin
28% Gryffindor
8% Hufflepuff
Blood: Pureblood, but he doesn't really care about such things.
Wand: (Old headcanon, not Pottermore checked and not made by Ollivander) Oak, sturdy, 11 1/2 inches, dragon heartstring