I worked recently on a matrix for my team and found it to be a great exercise to refine my thoughts on testing. Here is an example topic, Defect Management.

Here are a couple of images of the Skill Matrix I developed and mentioned above:

My matrix covers the following areas. You may want to add or remove to suit.
A great test matrix covers all the roles and experience levels.
It should cover these major areas with increasing levels of capability, this is not exhaustive but my initial pass and could be supplemented by any of you reading this:
Defect Management
Clear communication, Reproducibility, Proper Prioritization, Isolating (minimal steps to reproduce),
Advance Defect Management
Root cause analysis, Risk Management
Modelling and Planning:
Test plans, Mind Maps,
Test Design:
Selecting heuristics, Black Box Techniques, White Box techniques, Combinatorial Scenarios
Test Approach:
TDD, Identifying appropriate techniques
Automation:
Tool selection, GUI and lower level test automation, working with developers, Continuous improvement integration
Business knowledge:
Product knowledge, Company/Culture awareness, cross departmental interactions, Industry interactions (learning from other testers, presenting at trade shows, writing papers)
Technical Skills:
Networking, Databases, OSs, Coding, Development Frameworks, Presentation systems (Client, Web, Mobile)
Leadership:
Teaching/Mentoring, Learning, Research Skills, Deductive reasoning, Pairing, Communication, asking questions, Critical Thinking, Systems Thinking, Time Management, Multitasking, Monitoring Progress, Testing Advocacy, Customer Advocacy
Communication:
Situational awareness, Social Skills, Diplomacy, Writing/Presentation Skills
Risk Management:
Risk Assessment, Risk Control, Influencing overall development with a view to improve testability
If you need more help please let me know.