TC's for Pen:

Functionality :
 1. how is the writing as per the specification (.5,.6).
 2. Check whether the pen is writing able to write on other 
matterial(wood) other then paper.
 
Usability: 
 1.How is the look of the pen and brand also.
 2.What is the color of pen cover.
 3.What is the color of pen's ink.
 3.Check whether the pen is with cap or not.
 4.Check whether pen is ball or ink as per specification.
 5.Check the grip (thick or thin)as per the specification.

 Performence:

1.Check whether the pen is able to writing in any climate
(summer/winnter..)
2. Check how many pages pen can write continuosly with out 
any problem.

Reliability:

1.If pen fall down then check whether pen able to write or 
not....

Supportability:

1. whether the refile or ink can be changed or not(use and 
through).


And try the remaining...