Each of the bithsigns now drastically changes the gameplay, allowing more playstyles and improving replayability of the game. When rebalancing, I tried to preserve and enhance the distinctive features of most signs, where possible.
---------------------------------
New bithsign balance:

Warrior
-Main idea: The hit chance bonus allows the Warrior to use any weapon quite effectively without prior training. This is complemented by a strength bonus that increases melee damage and makes heavy armor easier to use thanks to the carry weight bonus.
-Constant effect: Fortify attribute "Strength" by 25
-Constant effect: Fortify attack (chance to hit) by 25

Lady
-Main idea: Lady's mind control ability works on fairly high-level targets, allowing to turn targets on their allies in combat. Also, this spell greatly facilitates theft, because. hypnotized targets do not inform guards; if there are several targets, they can be taken one by one to another place, and then theft can be committed without witnesses. The Personality bonus makes social gameplay easier, while the Endurance bonus increases Lady's survivability.
-Constant effect: Fortify attribute "Personality" by 25
-Constant effect: Fortify attribute "Endurance" by 25
Special Ability: Once per day, command a humanoid or creature up to level 20 for 45 seconds.

Steed
-Main idea: This sign gives maximum mobility to its owner.Incredible stamina regeneration allows him to constantly run, jump and land strikes, and the Feather effect ensures that heavy armor does not slow down the Steed.
-Constant effect: Fortify attribute "Speed" by 25
-Constant effect: Regenerate 4-5 fatigue per second.
-Constant effect: Feather (current carry weight reduction) 100 units

Lord
-Main idea: The lord gains incredible survivability thanks to constant regeneration and resistances. His only weakness is fire.
-Constant effect: Regenerate 1-2 health per second
-Constant effect: Cold resistance: 25%
-Constant effect: Lightning resistance: 25%
-Constant effect: Poison resistance: 25%
-Constant effect: Magic resistance: 25%
-Constant effect: Weakness to Fire by 75%

Mage
-Main idea: A fortified Willpower allows the Mage to cast any spells with a higher chance, while a bonus to magicka allow to cast more spells or more powerful spells.
-Constant effect: Fortify attribute "Willpower" by 35
-Constant effect: Fortify maximum magicka by (1 x Intelligence)

Apprentice
-Main idea: Unlike the Mage, Apprentice doesn't have a magicka bonus, which limits the maximum potential power of his spells, but constant magicka regeneration allows the Apprentice to spam weaker spells constantly, and this regeneration can be boosted even more by his unique spell (which costs health). Just like in the vanilla game, the Apprentice has a weakness to magic.
-Constant effect: 1-2 magicka regeneration per second
-Constant effect: Weakness to Magic 100%
-Spell for 10 health: Increases magicka regeneration by 3-5 points per second for 15 seconds

Atronach
-Main idea: The Atronach has maximum mana pool in the game, allowing him to cast the most dire spells. Moreover, 50% of incoming spells are reflected back to enemies, making the Atronach a decent mage-killer. The downside of Atronach is still Stunted Magicka, which means he will have to heavily rely on potions or enchanted items to restore magicka.
-Constant effect: Spell Reflection 50%
-Constant effect: Increases maximum magicka by (2 x Intelligence)
-Constant effect: Stunted magicka (magicka is not restored while sleeping)

Ritual
-Main idea: Ritual's ability to constantly restore attributes allows owners of this sign to rely on spells with "Damage Attribute" effect without fear of being reflected back. Magicka pool of Ritual is quite decent because of magicka and Intelligence bonuses. Intelligence bonus also allows the Ritual to use Alchemy and Enchanting more effectively. And like a cherry on top, 25% of incoming spells are converted to the Ritual's magicka.
-Constant effect: Spell Absorption 25%
-Constant effect: Fortify attribute "Intelligence" by 25
-Constant effect: Fortify maximum magicka by (0.5 x Intelligence)
-Constant effect: Restore all attributes by 3-5 per second

Thief
-Main idea: Sanctuary effect of the Thief is well-combined with light armor (or no armor at all), granting maximum mobility and carry weight without loosing survivability. Fortified Sneak skill allows the Thief to hide and pickpocket more effectively.
-Constant effect: Sanctuary (attacks dodge chance) 35
-Constant effect: Fortify skill "Sneak" by 20

Lover
-Main idea: The Lover's paralyze spell is almost guaranteed to hit the target because of the Willpower drain. Moreover, this spell cannot be reflected back to the Lover because of paralysis resistance. Fortified Agility, Acrobatics and Athletics will allow the Lover to land strikes more accurately and be quite mobile in combat.
-Constant effect: Fortify attribute "Agility" by 25
-Constant effect: Fortify skill "Acrobatics" skill by 15
-Constant effect: Fortify skill "Athletics" skill by 15
-Constant effect: Paralysis resistance 100%
-Spell for 10 Magicka: Paralyzing Touch for 30 seconds. Before inflicting paralysis, the target's Willpower is reduced by 1000, increasing the chance of paralysis.

Shadow
-Main idea: The owner of this Sign gains the ability to turn invisible with minimal mana cost and zero illusion skill. Also, even when the invisibility breaks, the Shadow will still be hidden by the 30% chameleon. Speed bonus will be useful both when traveling and in combat. While the spell is active, the wearer takes sun damage, so the time of day must be taken into account when playing as Shadow.
-Spell for 10 magicka: For 60 seconds, the caster gets: Invisibility, 30% Chameleon, Fortify attribute "Speed" by 15. During the spell time, sun damage is received (1 per second)

Tower
Main idea: Luck bonus and stamina regeneration allows the Tower to have more success chance of every action in the game, making it a very versatile Bithsign. Constant creatures/magic/keys detection allows to hide from enemies and seek treasures. Magicka bonus, combined with alteration/mysticism/illiusion skill bonuses, amplifies a Nightblade gameplay style, raising success chance of such spells as "Open", "Telekinesis", "Invisibility" and many others. If you prefer lockpicking istead of using alteration, the Tower also has a "Security" skill bonus.
-Constant effect: Fortify Luck by 25
-Constant effect: Fortify maximum magicka by (0.5 x Intelligence)
-Constant effect: Fortify "Alteration" skill by 10
-Constant effect: Fortify "Mysticism" skill by 10
-Constant effect: Fortify "Illusion" skill by 10
-Constant effect: Fortify "Security" skill by 10
-Constant effect: Regenerate 1-2 fatigue per second.
-Constant effect: Detect creatures 200 feet
-Constant effect: Detect magic 200 feet
-Constant effect: Detect keys 200 feet
-Spell for 15 magicka: Open 50 (on touch)

Serpent
-Main idea: Serpent is given a very cheap and effective curse, which can be spammed to debuff or even kill enemies (damage is dealt over time though, so you'll have to run away from cursed targets while they're loosing stats and health). This spell cannot be reflected back to the Serpent because of Magic and Poison resistances.
-Constant effect: Magic resistance: 100%
-Constant effect: Poison resistance: 100%
-Spell for 5 magicka, distant cast, single target: Deals 40-60 poison damage to health, 120-180 damage to Fatigue, 20-40 Damage to Speed and Agility over 20 seconds. The target is also affected by 15% sound and 15% blindness, as well as 20 penalty to Speed and Agility for the duration of the spell.
---------------------------------
Known Bugs
If you're using original Morrowind engine (not OpenMW), It is possible that when loading a saved file, a Feather effect on your character will cease to reduce your encumbrance. Extra weight will still be dumped on you when the duration of the effect expires, and as a result you'll still have a non-zero encumbrance rating even when holding no items. If this happens to your character, it can be fixed by using the following console commands:

• player->additem "misc_com_bottle_01" 1 (any item will work, but this bottle weighs 1.0 and is unlikely to be in most players' inventories.)
• player->removeitem "misc_com_bottle_01" n (where n is the amount of excess encumbrance plus 1)
  

Installation:
1. Place the .ESP file to the Morrowind/Data Files folder
2. Activate the .ESP file in the game launcher
3. Start a new game


My other mods:
1. Playable Vampires
2. Easy Enchanting
3. Fatigue Consumed Only In Combat
4. Start as a Vampire