Amber is transformed resin by application of heat and time. It's not particularly hard (scores a 2/10 on Mohs, compare to iron which is 4/10), nor is it made from any particularly rare elements. Amber is made from resin, resin is mainly made from turpenes, which can be derived from isoprene formulas (that is, a multiple of C5H8). It's just carbon and hydrogen. It's got similar properties to tar in that sense. You can play around with it to get terpenoids, which contain a few drugs, some odd flavors, and flammable substances. But that's not what you're looking for.
Injecting it into a human isn't a great idea, I'm not even sure how'd you go about doing it, considering that it's a crystallized solid. You can add it to iron and forge it in to get carbon-infused iron which is stronger than normal iron - but that's just what steel is. If you wanted to try something really weird, you can dunk a sword in resin and leave it to crystallized to amber over a few centuries, in which case you will get an odd sword which may have a far stronger surface from the iron-carbon interactions. Or you may not, I have no idea what would happen. (And, for technical reasons, if you're doing that, you want a mace, not a sword.)