Dude, this is a game where the grand archer uses his fists 90% of the time and the guy whose fighting style is clearly a saber yet class is grand assassin(formerly)

Uh, ok, maybe it's less about the fighting style and more about...her psychology?

I mean, when you look at it, PHH Morgan ironically suits her being a Berserker alot more, because all of her insane deeds against Camelot definitely looks like the work of a mad witch.

Then there's the whole Jeykll and Hyde thing with her also being Vivian at the same time.

But Lostbelt Morgan doesnt have that split evil insane other personality self thing because she became Queen of Britain.

So like....even some Berserkers are obsessed, but she doesnt seem to have anything much to be obsessed about left, if you compare her to other Berserkers who are obsessed with something in some way. In fact, its like she has nothing to rage for left.

Welp if you're talking about her obsession then her obsession of protecting her "britain" could be the thing

She’s a tyrant. That’s enough to qualify as a berserker. Every tyrant in any history or mythology has some inhumane aspect of their psyche.

Well FGO servant classes has been really stretched wide as the FGO progressed for 8 years. But yea as some above me put it, her obsession does indeed qualify her as a Berserker.

She cares not for the world or its inhabitants whether from PHH or the LBs. Even if all other places in the world burn its doesn't matter to her, so long as her Britain remains safe she is content.