Hi, a year or so ago I bought a 6’6” medium heavy moderate fast action rod not knowing about rod power and actions at the time. I’ve been using it as a topwater rod for spooks and poppers and it’s been doing quite well. Would it work for a squarebill or spinnerbait rod as well? I will be putting 14lb copolymer on it this year. Thanks!

If the rod loads and casts properly it will work fine. Should do well ripping Traps too. All you can do is try. Specs are too subjective to tell for sure otherwise. 

It should work no problem for squarebills.  I prefer a fast action for spinnerbaits but last week there was a thread where people were saying they'll use a moderate on spinnerbaits.  It all boils down to personal preference, you'll either like it or you won't and you're not going to know until you try it.

Will work great for spinner baits and chatter baits.