The idea that a spirit or saint is used for one thing and one thing only is problematic on many levels. Firstly, these are non-corporeal beings. We don't use them. We should discourage this language whenever possible. We pray for their aid, we beg for their intercession, at best we work with them - we certainly don't use them like kitchen appliances.
Secondly, a saint or spirit may be famous for working in a certain area but that doesn't mean that's all they can or will do. This is such a flawed, mechanistic, two dimensional way of looking at these beings - and one that reflects a fundamental misunderstanding about their underlying reality. Moreover, it's rather cynical if you think about it and does them a great disservice.
So I would like to suggest a different approach to this. Instead of looking at a saints 'stats' to see which would be good for your next working - far better, and more fruitful in terms of results, would be to take some time to consider with which saint it is that you have that special relationship and found your work on that. Because, after a while you will begin to notice some of them have a unique and powerful connection to you as a spiritual worker. This can manifest in a couple of ways.
For instance, you may find that contact with a certain spirit or saint comes to you by unusual means: you are gifted a statue; or you find a holy card in the street; you have a dream or vision about them or are otherwise brought into contact with them in some surprising and meaningful way. These kinds of events are special clues that a spirit is about to enter your spiritual framework, and would like to help in your work and establish a relationship with you.
The truth is that in reality the spirits and saints choose us.
You will find that a saint or spirit whom you form this kind of connection with (as apposed to the shopping for cewl powerz route) really moves and gets things done when you petition them. There is a potent flavour to any work you do with them because you know them very personally. What's more is you might find they will work in numerous different areas besides the thing that they are famous for. And they will begin showing you unique ways in which they will work for you alone.
I would like to dedicate this post to the most miraculous and marvellous Saint Joseph. This saint has blessed me by working in numerous different ways over the last couple of years and always startles me with his compassion and power. My his name be elevated in Gods celestial territory!
Prayer of St. Joseph
Oh, St. Joseph, whose protection is so great, so strong, so prompt before the throne of God. I place in you all my interests and desires. Oh, St. Joseph, do assist me by your powerful intercession, and obtain for me from your divine Son all spiritual blessings, through Jesus Christ, our Lord. So that, having engaged here below your heavenly power, I may offer my thanksgiving and homage to the most loving of Fathers.
Oh, St. Joseph, I never weary of contemplating you, and Jesus asleep in your arms; I dare not approach while He reposes near your heart. Press Him in my name and kiss His fine head for me and ask him to return the Kiss when I draw my dying breath. St. Joseph, Patron of departing souls - Pray for me.
This prayer was found in the fiftieth year of Our Lord and Saviour Jesus Christ. In 1505 it was sent from the Pope to Emperor Charles when he was going into battle. Whoever shall read this prayer or hear it or keep it about themselves, shall never die a sudden death, or be drowned, not shall poison take effect of them; neither shall they fall into the hands of the enemy; or shall be burned in any fire, or shall be overpowered in battle.
Say for nine mornings for anything you may desire. It has never been known to fail, so be sure you really want what you ask.