Im a student physio/physical therapist so maybe I can be of some assistance.
This probably comes 10 years later than it should’ve (not ten years too late kind you): a fracture that heals without complication and appropriate rehabilitation is carried out in the weeks/months after there should be no reason that you cannot come back as strong and, in time with appropriate loading, even stronger than pre injury. This still applies 10 years down the track. Try not to use your past injury as a crutch or an excuse.
When you say you fractured your “arm” are you referring to the forearm, the upper arm near the elbow, mid shaft or up near the shoulder?
Firstly a slingshot, elbow sleeve or other assistive/supportive device will not help you unless the pain is loading related which kind of defeats the purpose anyways. A brace is usually used during that iffy period after a fracture where bone is healed enough to put weight thru it but not fully healed. It would not be of assistance unless you have refractured. You’d probably know if this has happened.
It is highly unlikely that your arm is injured. When we think of injury it’s strains, sprains, tendinitis etc. that have little to do with previous fracture. These usually have a history of their own. Is this the kind of pain or injury you’re experiencing? Or is it something that’s been around after your fracture.
Pain is a response to harmful or potential harmful stimuli. After fracture tissues can stiffen and scar tissue can be formed. Whole joints can become stiffer. Stretching or tensioning of stiff tissue can cause pain. This is just one potential source of your symptoms so would need more questions e.g. location, nature etc. and examination to zero in on the culprit.