Welcome to the community!
1. Some people might generously go into PvP1/2 with an all weapon/shard/nymph deck. Usually they are not competitive, so the opponent can easily win the match and get the chance to spin the rares.
2. Yes, weapons can only be won through spins. Many AI3 decks have weapons, so you have a chance of winning one off them. Also, winning a consecutive number of games in Arena will give you a special spin, which provides a high chance of winning a weapon of shard. For more info on Arena, visit the
wiki.
3. If you decide to upgrade some cards, I suggest you to look
here for some popular deck ideas. Some of them can let you farm different AI level more efficiently, so you can have more electrum to improve your card base.
