Unlocking information on weapon upgrades

You will see the stats of an unlockable weapon as soon as you have gathered all items required to craft it.

Without any external resources the only way of finding out what those items are, is guessing. There are some indicators of where the items are from (Color, Icon etc) but It's no guarantee since sometimes monsters drop materials with icons similar to let's say an ore.

Don't worry though. If you're playing the game and hunt as many different monsters as possible you'll see all of the stats soon enough!