Thor (1962 1st Series Previously Journey Into Mystery) #459 1st Appearance of Thunderstrike

Thor and Eric are fighting over Sif and Mjolnir. They fight throughout Asgard, and even though Odin knows that Amora is behind Eric’s bewitchment, he condones it, for he has other plans. Summoning a bolt of lightning, they are blasted apart, and Eric regains his senses. He relinquishes Mjolnir and prepares to leave, saying farewell to a tearful Sif. Thor flies him back to Earth and gives him a gift from Odin, a walking stick. Thor flies back to Asgard, and Eric, noticing that the stick is familiar strikes it on the ground. It transforms him into Thor again, but the stick has transformed into a mace – Thunderstrike.

Continued in Thunderstrike #1