Hit Points and Damage are abstract points use to measures one's capacity to take damage, or the power to inflict damage. Not all damage needs to be physical injures, but merely the loss of physical energy, the will to fight, and one's personal luck. That is, someone who avoids a fire blast (as a "save or take half damage" attack) would come out untouched, but the close call would mean the character would not be as lucky the next time. By the normal rules, reaching 0 hit points means death, but there are alternatives to this.
This page deals with house rules on the topic of Hit Points and Damage, including injury tables/effects, special forms of damage (fire, acid, etc.) and so forth.
Base Damage Dice
|Strength Score||Base Damage Die|
|20+||_+1d6 per point over 19|
With this system, characters get an additional damage die based on their Strength score, and that die serves as their base unarmed damage die. What rolling damage with a hand-to-hand weapon, the player rolls the base damage die with the weapon's damage die. So a man with average strength (9-12) attacks with a shortsword, the player rolls 2d6, while an extremely strong man (STR 18) can do that with his fist. If that strong man is armed with a shortsword, he could do 3-18 (3d6) points of damage in one strike. Anyone with a Strength of 3 is a total weakling — their baby-slaps yields no damage — while regular weaklings (STR 4-5) do 0-2 points with their puny arms!
With (non-throwing) range weapons, just add another die to the damage dice. This could make primitive firearms nasty, as they would hit with 2d10 or 2d12, but advanced firearms would only have an extra d6 or d8. Throwing weapons should still use STR adjustment, as if they are used in melee. Advanced melee weapons should be treated like primitive weapons with added damage effects. That is, Batons should be treated like normal Maces (1d6+STR dice), but with +15 electrical damage for Energy Batons. As an alternative, advanced melee damage could have variable damage instead of static bonuses (+2d8, instead of +16). You only need to add an extra die to the punch of a LEMA power suit, but heavier EMAs do enough punch damage.
With monsters, just add an extra die to their damage score, to keep the monsters from being underpowered. It in notes 1d4, then it does 2d4 instead. If it says "1d6, or weapon type" — typical with most humanoid creatures — it should say "1d6 plus weapon type" instead.
If you are using magic weapons in your MF game, each magic 'to-hit' bonus adds a dice to damage. So a basic +1 sword would do 2d8+BDD (base damage dice) instead of 1d8+1+STR adjustment. In a more extreme case, mixing a Vorpal Sword (a +3 magic weapon) with a Warp-Field Sword (a +2 equivalent weapon) to emulate Thundarr's fabulous Sunsword, would do 4d8+16+BDD (alternatively 6d8+BDD), which can lower the opponent's AC by 2 (on top of the +3 to-hit), and kill or dismember them on a roll of 20 or more.
(Base Damage Dice by Malcadon)