Phantom Abyss

You unlock tier 1 whips by collecting tier 1 relics. I am not sure if certain relics will unlock the certain whips, however you need to collect each unique tier 1 relic anyway for another achievement so I will tell you how to get tier 1 relics. There are 15 tier 1 relics including the tutorial level relic. You can check your progress in the collected relics room, there are 15 pedestals (1 for each relic) on the lowest level here. You will unlock a few tier 1 relics while playing through adventure mode, but you will rank up pretty quickly and soon you will start collecting tier 2 relics.

To mop up tier 1 relics, you should play classic mode. The way classic mode works is that you will start off with 3 level 1 temple stages to play through, and at the end of the third stage you will have the choice to go downstairs to the final stage which has a door to unlock and level 1 relics to choose from or you can continue on to another 3 level 2 stages. Go downstairs and unlock the door by lighting the braziers. Once you're in the treasure room there will be originally 8 unique tier 1 relics to choose from. If one of phantom players was able to make it this far and collect one of the relics, the unique relic on that pedestal will have been replaced by a bag of sand. Now just collect any relic you dont have and repeat this process until you have all the tier 1 relics and tier 1 whips. While you're doing this, you can work on prestiging your tier 1 whips as well.

With the 1.0 release, you simply need to complete all 6 Ruins temples. This will also unlock the "They belong in my museum" achievement.