I have been trying to research but just cant seem to really find…
When fusing gear to upgrade to the next level…is it required the gear to BOTH be 3 “pip” items when fusing for the best quality?
Or can get use a 3 pip and a 1 pip and fuse and still get the best results?
You do not have to have matching pips while fusing gear to get the best results. Just make sure you have the correct pip you want to upgrade.
Quote for truth. Nothing makes my butt clench more than when I’m about to do a fusion between my 3 pip item and my 1-2 pip item. I triple check because I KNOW that one of these days I’m going to make a very bad mistake 
It’ll warn you if you do, but with only one extra confirmation dialog. I fused an old basic 3-pip weapon into an extraordinary 2-pip weapon once. Something along the lines of “you’re about to fuse a higher power item into a lower power item. The higher power item will be lost. Do you wish to continue?” I don’t think there’s a similar warning for fusing a low power extraordinary into a high power basic. At least, I haven’t seen one for all the one pip belts.
OK thank you for the replies this helps a LOT
Signet and glyph you need the same, weapon only the same type and talisman is if I remember right anything goes.