Guysbert was supposed to be married with Bean, but when she disagreed to be wed with an outburst of anger, Guysbert's head was impaled on some nearby decor. This didn't in fact kill him, becoming a running gag for the rest off the season.
In episode 7, a callback to his near fatal wounding in the first episode sees him used as a test subject for the elixir of life. After initial success, he finally died when he removed the sword from his head and his brain fell out.
Had his wedding to Bean been a success, he would have taken her back to Bentwood with him and the plot of Disenchantment would have been unlikely to unfold.