To be honest, her history is pretty normal (by the standards of her time).

Woman launched a huge cattle raid for prestige, which was very common in pre-modern times. For example, Castor got killed on a cattle raid that happened after Helen got carried off, which we know because she doesn't know why she doesn't see her brothers on the battlefield in the Iliad. Similarly, one of Heracles's labors was a super-sized cattle raid, while another of Heracles's labors was a super-sized horse raid.

Besides that, Medb's multiple partners was pretty normal for pre-modern rulers. Hell, her standards for her lovers are actually pretty sympathetic considering that her first marriage ended poorly, which was eventually followed by her ex-husband raping her at an assembly at Tara. The sister-killing was too much, but once again, it was the kind of thing that a lot of pre-modern rulers engaged in.