My father's theory on Wurt

While me and my father were discussing while doing art, I talked about the mystery of Wurt's broken horn. The description of what Wurt is of her being a guard merm. Yet something's amiss:

Her horn is still broken when she's become a re-juvinated guardian merm with a new merm king.

Here's a new merm guard

Annnnnnnnnnnnd a merm guard when the king is dead.

So my father had a theory as to why Wurt is continually a lost merm guard:

Quote

When a Japanese lord is defeated, his samurai would lose power. If they weren't accepted by a new lord, they become a ronin.

So my father is assuming she's a metaphorical ronin. Still, why did you think her horn is still broken in universe?