Test Engineer should have the ability to break the 
application.

in some companies white box tester r developers. they will 
test there  own module only . they will not do IGT for it.

A good tester take the customer point of view. Strong 
desire for the quality. And pays attention to evry detail.

  A good test engineer knows the boundary and scope of testing.
Test engineer's job is to break the system in order to built more
robust system that carries the fixes of the testing.Always
keeps in mind that it is done from the perspective of the
system requirements not from the specific feature alone.
A test engineer is not labeled as 'good,'by the number of
defects/bugs filed,but how critical the defects those were
filed by a test engineer.There are many activities that
makes a test engineer good, in testing of a product.A good
developer always makes a test engineer good.vise verse. 

   

A good test engineer has a 'test to break' attitude.
An ability to take the point of view of the customer
A strong desire for quality, and an attention to detail.
Tact and diplomacy for maintaining a cooperative 
relationship with developers.
An ability to communicate with both technical (developers) 
and non-technical (customers, management) people.
Judgment skills are needed to assess high-risk areas of an 
application on which to focus testing efforts when time is 
limited. 
Notice little things that others miss/ignore (See symptom 
not bug)
Good testers use files, Databases and all the other 
accoutrements of an organized mind 
Testers are fundamentally honest and incorruptible 
Last but not the least is “Patience