Advancing with Metalworking after 400

[Deborah]

Hello everyone,
now I reached Metalworking at 421.062 on the character that is planning to become an Artisan. I practiced with trigger nuts and small armor plates. Currently, I am at a dead end cause I can't raise it up further, even though... see here.
You are studying the following skills:
Armor Use: 3.702 remaining
Metalworking: 4.39 remaining
Shield Use: 1.675 remaining
Would it be possible to add things that can allow one to go further up with the skill?
Thank you so much.
P. S. I was thinking where to write this, and wasn't coming up with another better, suitable category where to throw this thread, for this I got it here.