The first is the fighting caveman Hok (recently collected by the magnificent Paizo for the first time). The second is Kardios, accidental destroyer and sole survivor of sunken Atlantis.
These latter stories were produced mostly for Andrew Offutt's "Swords Against Darkness" anthologies in the seventies. The second to last was included in Gerald Page's "Heroic Fantasy" collection in 1979. Written in the heyday of the genre, these stories, are playful and wry commentaries on mankind's willingness to enslave itself to self proclaimed gods and the acquisition of wealth and power.
Kardios is a harpist with long black hair, a strong, bronzed muscled physique and little fear. Post destruction of Atlantis he wanders the world simply seeking out what's new and unknown to him. Seeking to better himself he left the forests and woods of his back hills home and set off to the "gold and jasper palace" of the seemingly ageless Queen Theona. Overhearing his singing to her advisers she invited him in and asks him to sing for her. The song he sings for Theona is about her and a prophecy that says when she "grants to a lover the boon of a kiss, Atlantis, Theona, will drown in the sea." Theona simply laughs off the warning and asks Kardios for a kiss. He gives her the kiss and the earth quakes and the seas spew up and Atlantis sinks beneath the waves.
There are but five stories telling us of Kardios' life and adventures. The first, "Straggler from Atlantis" introduces us to our hero and tells of how he washes ashore on a coast populated by friendly giants and an inimicable traveler from the stars. Here Kardios gains his sword of iron. This comes to serve him well in his following adventures letting him get around creatures unable to be hurt by mortal weapons.
The rest of the tales, "The Dweller in the Temple", "The Guest of Dzinganji" "The Seeker in the Fortress", and "The Edge of the World", follow similar arcs to one another. Kardios comes across something strange and hazardous to his health. Through his wits, charm, a dash of luck, and nigh magical sword defeats it, be it old god, old sorcerer or old social customs. For all the inventiveness and action there's never any real sense of danger. Kardios never really seems to be at risk of getting hurt let alone dying.
Nonetheless, the stories are fun. Time and again, Kardios is drawn in to situations where people, be they lotus-eating urbanites or gold seeking travelers, have allowed themselves to become snared by greed and fear. They have made accommodations to dire circumstances or beings in order to hold on to wealth or simply their lives. Kardios is able to detect these things, and, also, with sword and courage, pare away the black deals and devilish compromises to some sort of freedom. Which I think was a large part of what Wellman was doing with these stories. The stories aren't deeply philosophical tracts or anything. They're still about a sword swinging harpist fighting monsters and what have you, but, there is a little something else going on.
The stories are also much earthier than anything else I've written about before. Queens, princesses, mechanical women, amazons and chamber maids all fall at Kardios' feet and are willing to (and in some cases do) fall into his bed. And it's all fairly believable. His charm and dash are as real as they can be on a the printed page.
Unfortunately, it's tough to come by all these stories at this time. They've never been collected and I can only hope the good people at Paizo are listening. Right now you have to track down the Swords Against Darkness books (which you should have anyway, people) and Heroic Fantasy. Three stories, "Straggler of Atlantis", "The Dweller in the Temple" and "The Seeker in the Fortress" can be found in three of Isaac Asimov's Magical World of Fantasy collections. Still, you're looking at about fifty bucks on Amazon. Unless you feel a need to get the Swords Against Darkness anthologies (+ Heroic Fantasy) you're probably best waiting till some nice publisher binds them together for you.