Reaching level 30 will unlock 60 weapons. To do it faster, you will need to pay tank coins. There are several ways to unlock weapons by buying:
1) Buying a weapon pack costs 80 tank coins and unlocks 10 weapons. In general, higher numbered weapon packs are better.
2) Buying a retro weapon pack costs 120 tank coins and unlocks 20 weapons. The retro weapon packs are comparable to Weapon Packs 1 and 2.
3) The best deal is to go deluxe for 1 month. Doing so costs 20 tank coins and unlocks 20 weapons, double XP, and 2 tanks. These benefits last for 1 month if you choose the option that costs 20 tank coins. You can also buy 3 months of deluxe for 50 tank coins, a year of deluxe for 150 tank coins, or lifetime deluxe for 300 tank coins.
The ultimate arsenal quest can be completed with no deluxe or packs? only with level and prestige?
You don't even need to prestige. Level 30 is enough because you start with 30/31* weapons and unlock one each level.
*Technically, there are 30 starting weapons, but Blaze is a little different from the other level unlocks. It's "level 1" on the level unlock path, but it can't be used on substitution turns. Don't worry about the technicalities too much because you'll definitely have Blaze at level 2, making it 32 weapons at level 2, including the unlock of Back-Roller at that level.
@XxmoyaxX The best way to gain XP for me was to collect 20 tank coins and activate deluxe. Or you can find someone who is willing to play with you (1vs1) 30 turns based game and come close to each other so you can always hit the other player. This is what I was doing.
Half the weapons in the game do more damage if you are farther away from the other player. So getting close means you get way less xp. Getting close in 1v1 is a terrible way to get xp quickly and angers a lot of players.
3v3 for 30 turns also has a way better multiplier than 1v1 and the time spent in the end nets you far more xp per amount of time. I personally get 400-450 xp minimum per 30 turn 3v3 match (if you are deluxe that would be 800-900 per match).
Overall, the best way to gain xp? Learn how to shoot in the practice range. If you aren't a good shot, you waste time on misses and get far less xp per amount of time.