Is there any use for a three level-based sub-ability

[le Redoutable]

Like, starting at level 1, and upgradable two times??

 

[le Redoutable]

So, a sub-ability is produced by the link of two stats
For example,
Comeliness = Con x Cha
This means it starts at 1, when neither Con nor Cha have proficiency in it.
Then, if say Cha gets proficiency in Comeliness, Cha climbs one level, and Comeliness climbs also one level;
Then, in order to reach max level ( I e. Level 3 ), one needs to climb Con by one level...
Stats aren't like in dnd, they range from 0 to 5

 

[le Redoutable]

Then if a given class is composed by assemblage of three sub-abilities, it will range from 1 to 10 ( as shown below )
1 -> 3 x 1-> 3 x 1 -> 3 gives 1 ---> 27
1 -----> 1
2 -----> 2
3 -----> 3
4 -----> 4
6 -----> 5
8 -----> 6
9 -----> 7
12 ---> 8
18 ---> 9
27 --> 10

 

[le Redoutable]

Then,one could imagine, given five classes ranging 1 to 10 your overall ( or global ) pentaclass level would 5 to 50...
Actually, in order to give versatility in the highest levels , pentaclass level should be limited to 42;

 

[le Redoutable]

Given a max level at 42 means your five classes may be something like
10 + 10 + 10 + 10 + 2
Or
9 + 9 + 8 + 8 + 8