Thunderblade and Great Thunderblade respawn areas

Solution 1:

The stalnox in Hickaly Woods drops a Thunderblade, and the one in the Hyrule Castle dungeon drops a Great Thunderblade.

Further reading:

  • http://zelda.wikia.com/wiki/Thunderblade
  • http://zelda.wikia.com/wiki/Great_Thunderblade

Solution 2:

Thunderblades can also respawn in the Coliseum, just north of the Great Plateau. See my answer about where to get frost blades. The same answer applies for Thunder Blades (+ spear) and fire weapons as well.