How do you learn the abilities?
There'd be 2 options:
1) Change the name of the ability via the event system.
E.g. using the Add Game Event of the ability's level to change the name. The ability is available as selected data via the key action, which allows to change it's name using a Change Selected Data Name node.
2) Have each level as it's own ability with the name you want.
You can use the event system to replace the previous ability - either using the Add Game Event (like in option #1) or if you e.g. learn new abilities via events anyway, directly in that event.
There's also the option of using research trees instead of ability trees - they basically do the same thing but offer more variety (that's why ability trees will be gone in ORK 3). E.g. learning an ability via a research tree can also use an event and remove the previous ability that way (or rename it via selected data).