I could use "one more tool in my toolbox" to describe a final addition to the various methods I have for doing something. However, I'm not sure about "tool" occuring twice in such a short phrase. "One more arrow in my quiver" sounds a bit weird. "One more weapon in my arsenal/armoury" sound too martial. Is there a more elegant formulation along the lines of needing "one more" something or other in "my something or other"?
The ability to tap dance is "...just another tool in my toolbox." meaning that you are highly qualified and it's no big deal, it is just one of the many skill you posses. You can swop between different tools to get the job done.
An alternative could be
[having] another string to one's bow
which refers to the bow string of a [long]bow and arrow, that is, I have another string, so if the original one breaks, I can easily replace it with another and keep on shooting arrows [probably] at Agincourt.
If you need to acquire an additional skill, you could say: "I need another string to my bow." Meaning that if you cannot do that one thing [usually relating to employment] you cannot work and earn money.