This was an idea I came up with while thinking about random things. If you wish to provide criticism on this, please do so after reading this to it's fullest extent, thank you.
My idea is the "Weapons and Armor Testing Facility" (name is open to being changed, it's just a temporary name I came up with for it).
[What is it?]
Weapons and Armor Testing Facility (WAATF) allows for players to test out weapons and armor before they actually buy/craft them. It would be completely free to use. (much like Advanced Training)
[What does it do?]
WAATF would be a new building in haven (most likely in Town Square, since a building similar to it; Advanced Training, already is). When you go inside, there will be a medium-sized room that will have a character that allows you to select any weapons and armor you wish to use (whether you have it or not), You will have 4 weapon slots, regardless of whether you have the slots opened or not. Once you have your desired weapons and armor selected, you will be asked which family you would like to fight (beast, undead, slime, etc) and at what stratum. Once you have selected the desired weapons/armor and the desired enemy type, you will be put in an arena-like room that is larger than that of a normal "arena" level that you find in the clockworks. Each "round" will feature a stronger version of that enemy type (for example, slimes would feature Royal Minis first, then move on to things such as Jelly Cubes and Lichen, and eventually end with the Jelly King and Ice Queen (Regardless of the stratum you select, boss enemies will still appear the way they do in their respective stratum). You do NOT obtain crowns, heat, materials, or any other normally-obtained item while fighting in the WAATF, and after you leave the WAATF, you do not get to keep any weapons/armor you picked to use there (equipment you actually had in your arsenal you get to keep, of course). It is simply a free, yet effective way to try out weapons on various enemies before you actually get the weapon, versus having to go by the wiki's descriptions of the weapons (actually getting to test them is always better).
[What makes this any different from the Advanced Training?]
Advanced Training has but one enemy type - Training Bots. Which aren't the best for actually testing weapons out with, because they're neutral to everything. They're also very weak.
Advanced Training only allows you to try out weapons you already have. WAATF allows you to try out any weapon/armor you desire to try out, so that you can get a better idea of what weapons best fit your preferred fighting style, versus possibly getting weapons you might not like. It's annoying to spend all that time, crown earnings, CE, and materials, just to get a 5-star weapon that doesn't even remotely fit your preferred style.
Adding this would do NO harm to the community, NO harm to anything already in the game, however it would greatly benefit almost every player.
Honestly thought this should be added to advanced training tbh. Having a separate hall may conserve space but intuition would tell me Advanced Training Hall should provide this in a different room. (Like a backroom or something.)
However this idea is implemented, know that I agree with it and will thoroughly support it as is.