Y-Yuuji with Tyrant-san.

Except she believes basics should be applied.

There are also two words that are really important in Yuuji's eyes.

Player Intuition.

To avoid this being turned into a number/stat/power grinding role play (which isn't really what Ike-san wanted, Ike-san wanted something that revolved more around character development and context growth wise), Yuuji believes flat numbers should be left out completely. Player intuition is important. It dictates maturity, oversight, and a general willingness to put aside petty things such as personal pride for a greater cause. Yuuji feels with numbers involved, focus shifts away from role playing and players get their creativity gimped, not to mention lazy with their words.

By basics, Yuuji means this:

Fire is weak against water, so if your character is a Fire Mage that gets hit by water magic, you should obviously receive a greater amount of damage than your average Joe. Role play it out. Numbers don't have to be there necessarily. Elemental weaknesses and their general rule of thumb should be kept in mind and considered without them having to be forced down your throats with numbers.

If a target is wearing armor they obviously take less damage. Y-Yuuji is sure the capable role players here all know that. Again, numbers aren't necessary. Be mature about it. Basic physics, chemistry, knowledge. Fighting against armored knights and you're a(n) Thief/Assassin? 

-Fall back and gracefully call for the aid of party members.
-If you're alone you can just run. They'll get exhausted chasing you. 
-Go for the spots between the armor, trip them, do some basic actions. You don't need to be over dependent on skills. 
-Hinder their movements and act as annoying disruptions for your capable front/back line mages or warriors.
OR if applicable
-Surround them with fire and smoke them out of their thick and heavy armor. Players still feel pain/heat. NPC as well. Unless they're possessed armor mobs/undead/some other heat/pain resistant creature.

This is role playing and Ike-san has given us a vast variety of freedoms. We get to be creative~

Even characters with high levels can't fight the terrors of gravity. While this is a video game like Silver-san mentioned, this isn't any regular video game, it's a VRMMORPG. All players are able to jump a set distance, for a set height. Players with armor obviously can't jump as high. Players with class distinctions should obviously be able to jump higher. If you fall off a ledge, you'll take damage. Unless an ability or a circumstance arises, natural instances of damage should be applied.