Look at her Rankups/Interludes.

Old servants often got their Third Skill unlocked after you clear them.

Medusa Rider was also the same iirc.

@GudakoAlter61 but it says ascension 3 times?

That's weird.

Look riiiiight below that.

Clear "No Matter How Many Times the End Comes"

Sounds like an Interlude to me.

Clear the interlude to open the skills. Year 0 servants (or day 1 servants) only have 2 skills at the start of the game. That's why they need interlude.

Good old times where a handful of servants had three skills.

No you are not, you have to do Nero's Interlude to get the 3rd Skill.

Ah, the memories!