I have thought of different ways to make characters in my RPG gain skills through weapons. So I came up with a solution that seems manageable (for the most part). Let me explain it so it's easier to figure out what my problem is. Each character has a different Experience amount (and therefore a different level) for each type of weapon (swords, axes, spears, bows, etc). Therefore, there is no "overall" level for your character. The more you use a type of weapon, the more exp you will have for that weapon. Switch weapon types and your exp and level will change. Don't use certain types of weapons for long enough and your exp will actually drop (a way for players to "get rusty" with a skill). This system is meant to encourage people to specialize in one job/fighting style, and to avoid frequent "uber-powerful" characters. So far, this system sounds pretty good to me. The problem is, how are basic stats like HP and MP measured? Since your character has different levels for each type of weapon, should they be forced to stick with the same HP and MP throughout, or will it change according to the type of weapon? I'm a little iffy on the second choice, since it would be weird to have your maximum HP and MP suddenly change if you decide to go from using a spear to an ax.

The idea has been done before in simpler forms that still required normal levelling up, but I could see this working.

You should have a few item slots open to armor/magic items that influence your HP and MP. The armor protects you and thus lends you more hit points while the magical items somehow increase your MP. Have like three or four slots that can either be filled with all magic items (amulets, rings, crowns) or all armor items (helmets, breastplates, gloves, boots, etc).

If you change your vocabulary and change "experience amount for each type of weapon" to "skill level", you have a description of a pretty standard skill-based game.

RDragon1 is correct, this isn't much a separation from skill based games. Ultima Online is a notable example of a skill based game.

A number of systems handle HP and MP either by stats that grow through use, or through actions that interact with them directly. For the former, HP is based off your strength stat, which grows as you use strength based skills. For the latter, taking so much damage would increase your overall HP by a small amount. Casting X number of spells would increase MP, and so forth.

Tychon and EvilBean, I like those ideas. I haven't played many PC RPGs (more of a game console man myself) so unfortunatly I'm a bit behind on how skill systems have advanced. If I were to base growth on HP and MP based on equipping items, that leaves me two different ways to apply them.

1. Increase the HP/MP capacity with items and weapon skills

2. Keep the HP and MP the same for everyone, but increase their efficiency with preserving HP/MP with the items and skills. (i.e. with enough use, a spell that used to require 10 MP to use, now only needs 8 MP.)

Right now I favor the first one since it's just less confusing and easier to code in practice.

Make the HP and MP skills.

All magic use slowly increases the amount of MP "skill" you have.
All combat increases your HP skill.

Might work if you could play with the MP/HP skill ramp. By then though you are simulating an experience driven system.

Most RPGs have attributes (strength, dexterity, constitution, intelligence, wisdom, and charisma in D&D and lots of others that borrowed the system from them). Make these attributes level with use as well. Then base HP and MP off them, probably MP on intelligence or wisdom and HP on constitution.

What if you dropped weapon categories and levelled your knowledge with the weapon and armor itself. That is to say, while equipped with a given sword, it modifies your stats along some set, HP+4, MP+1, STR+3. You fight, get the experience, and when you hit the level (100 points?), you keep those stat bonuses when removing the weapon.

As a side effect, it'd encourage players to find every item they can.

this idea was used in Wow...raise hp xp every time your character gets hit. raise mp everytime it uses a spell and so on...

Apart from what you've said in the first post, Ultima Online also had a few more features:
1) a maximum limit of skill points that a character can have (axes+swords+whatever else <= 400 for example). This prevented the people in the game to become overpowered even if they specialized in a certain skill.
2) Skill locking - you could freeze a certain skill from raising/dropping in order to protect it for decay over time, or for eating up valuable skill points from the maximum total.

As for HP/MP , you can relate them to certain stats such as strength (that could possibly raise from using melee weapons). HP can also be proportional to an average of your melee skills (thus it will remain the same no matter if your skill with a new weapon sucks). MP.. same thing.. use magic , grow powerful. You know better what you want to make of your game/system.

3rd edit:
The Elder Scrolls series uses a different leveling method:
you have 3 groups of skills, that you can choose at the character creation:
a) primary skills (3x)- grow the fastest with use
b) secondary skills (3x)- grow a bit slower with use than primary
c) minor skills (the rest) - grow the slowest

In the series you advance in level when you had 15 skill increases in your primary/secondary skills, plus some minor ones. You don't see the XP you have in a certain skill, but using it for some time (let's say swinging swords for some time) gives you an increase in that skill. Also, after a level-up you are prompted to distribute some points in stats (str,dex,int, etc). And you can grow stats related to the skills that you used to level faster than stats related to the other skills. For example , fighting in melee with swords/axes/whatever gives you an easier increase in strength or constitution, while fighting with bows gives you an easier increase in dexterity. You can increase something else if you wish, but it will cost more.