he was just a guy that was worthy to lift Mjolnir and gain the powers of Thor.... he replaced Thor on the Avengers roster for a while (while the real Thor had something to do in Asgard... can't remember what right now)
Masterson was later given an enchanted mace by Odin which gave him Thor-lite powers...... he tied his hair into a pony tail and called himself Thunderstrike
He's dead now
when he replaced Thor he had exactly the same powers as Thor, when he became Thunderstrike he was less powerful....... he could still fly and summon lightning and had high level super strength and invulnerability... but not to the same extent as Thor
he managed to get his ass kicked a few times in his own short run series:
But he did make the Juggernaut crap his pants when he almost decapitated him with the Blood-Axe (Same axe King Thor used to kill Desak)