I think he wouldn't be as strong as Thor, but he would be as skilled as Thor in fighting.
I don't so. Frey's children arent fighters, so is Frey?
^Frey's children aren't natural fighters. They are peace-loving. But I think they can learn to fight, at least for self-defence or in desperate measures.
Also, Frey isn't a bad fighter. Mimir, an Asgardian god, describes Frey as a general in the gods' army. Frey is fated to kill several important giants in Ragnarok.