Interpreting Low (and high) Ability Scores: The Mental Attributes

After multiple posts on the topic, 'An ability score of 3 is unplayable' I concluded that for me, the answer was to 1) Not allow starting player characters to have an ability score of <6 (3,4 or 5) by asking them to re-roll such ability scores, and 2) Evolve harsher in game mechanic effects to more effectively model what an ability score of <6 would represent, were that fate befall the player character or NPC.

Below are my tables for the Mental Attributes: Intelligence and Wisdom.
For both ability scores I include a descriptor to better help DM and player alike understand the effect of that ability score.

Intelligence Score	Mechanical Advantage B/X Communication Languages	Descriptor Score = IQ divided by 10	Jovial Priest House Rule Intelligence bonus gives languages, inspiration roll, XP Magic-Users can know additional spells in their spellbook/level up to their intelligence bonus
0		Non-intelligent or not ratable
1		Animal intelligence
2		< 2 Idiot: Profound retardation may be able to develop basic self-care and communication skills with appropriate support and training. Their retardation is often caused by an accompanying neurological disorder. Profoundly retarded people need a high level of structure and supervision. 2-3.5: Severe retardation: master very basic self-care skills and some communication skills. Many severely retarded individuals are able to live in a group home. 2-4 Semi-intelligent 2-5 Imbecile
3	Trouble speaking		Trouble speaking No playable character class
4-5	Cannot read and write	3.5-5 Moderate retardation: can carry out work and self-care tasks with moderate supervision. They typically acquire communication skills in childhood and are able to live and function successfully within the community in such supervised environments as group homes. 5-7: Low intelligence, Moron, Mild retardation: acquire academic skills up to about the sixth-grade level. They can become fairly self-sufficient and in some cases live independently, with community and social support.	Cannot read and write Inspiration roll not possible -90% XP
6-8	Write simple	7-8 Borderline deficiency 8-10 Average human	Write simple Inspiration roll not possible -20% XP Minimum for spell casting (must save vs spells to cast)
9-12	Read and write common + alignment	11-12 Very intelligent	Minimum Elf Adventurers Read and write common + alignment Inspiration 1in6
13-15	+1 language	13-14 Highly intelligent	+1 language Inspiration 2in6 +5% XP
16-17	+2 languages	15-16 Exceptionally intelligent	+2 languages Inspiration 3in6 +10% XP
18	+3 languages	17-18 Genius	+3 languages Inspiration 4in6 +10% XP
19-20		19-20 Supra-genius
21+		Godlike intelligence

NOTES & Links
Inspiration Roll Rules - since role playing an intelligence higher than one's own is very difficult.
Only Intelligence gives XP - and at low intelligence should be much harsher than standard rules.
Minimums are given for all player characters, spell casters (both cleric and magic-user) and elves.
Spellbooks - I have taken the B/X line that the number of spells in one's spellbook is determined by the number one can cast in that level / day. I have expanded this to allow higher intelligence characters to have an increased range of spells in the spellbook. I am planning to allow magic-users and elves to cast any spell from their spell book up to the their maximum number of spells / level / day allowance. Shock horror how non-Vancian. I just get sick of the default magic missile/sleep/charm person spells compared to any other choice and similarly at higher levels the total predominance of fireball/lightning bolt. I want to see more choice. Go on, cast that ventriloquism spell on that sleep immune enemy and escape. Maybe you just might, if you didn't have to sacrifice memorising sleep spell for that day.

Wisdom Score	Mechanical Advantage B/X	Descriptor Willpower, intuition, judgment, wile, enlightenment, spiritual/religious awareness (choose one or two to describe you)	Jovial Priest House Rule Wisdom bonus gives bonus to all saving throws, gives intuition roll Templar Cleric 1d4 known cleric spells / level, minimum known spells = wisdom bonus and choose which spells are known up to wisdom bonus else random
1		Bed bound
2	Non-combatant	House bound	Non-combatant
3	-3 on magic-based saving throws	Inactive, inert, senseless, craven, quivering wreck, witless	-3 on all saving throws Intuition roll: Right intuition 1 on a d6, Wrong intuition 3-6 on a d6. Save vs paralysis every morning or refuse to get out of bed, and Save vs paralysis every round of combat or flee
4-5	-2 on magic-based saving throws	Slothful, foolish, spineless, areligious, half-wit	Unable to cast cleric spells -2 on all saving throws Intuition roll: Right intuition 1 on a d6, Wrong intuition 4-6 on a d6. Choose: Save vs paralysis every morning or refuse to get out of bed, or Save vs paralysis start every combat or flee
6-8	-1 on magic-based saving throws	Lazy, imprudent, cowardly, fearful, insincere, slow witted	Minimum for Templar Cleric class -1 on all saving throws Intuition roll: Right intuition 1 on a d6, Wrong intuition 5-6 on a d6. -1 known cleric spells / level, unable to choose
9-12		Average	Intuition roll: Right intuition 1 on a d6, Wrong intuition 6 on a d6.
13-15	+1 on magic-based saving throws	Willful, thoughtful, shrewd, sound, devout, brave, quick witted	+1 on all saving throws Intuition roll: Right intuition 1-2 on a d6, Wrong intuition 6 on a d6.
16-17	+2 on magic-based saving throws	Driven, wise, philosophic, spiritual, courageous	+2 on all saving throws Intuition roll: Right intuition 1-3 on a d6, Wrong intuition 6 on a d6.
18	+3 on magic-based saving throws	Unbreakable, prophetic, beatific, Zen Master	+3 on all saving throws Intuition roll: Right intuition 1-4 on a d6, Wrong intuition 6 on a d6.
19+		Yoda

NOTES & Links
The Descriptor actively encourages the player character to choose one or two phrases that best sums up their characters ability score and supports better and appropriate role-playing for that score. It may seem strange that I have linked high wisdom to bravery and low wisdom to cowardly. This in my opinion reflects the drive and determination of the wilful person. The wilful person thinks they have something worth fighting for, the unwilful person has trouble getting out of bed in the morning and doesn't want or seek trouble.
It may also seem strange that areligious is equated to a low wisdom. This is not a go at Richard Dawkins! D&D, as given to us, is a world of gods and demons that grant clerical spells, that have always been linked to the wisdom ability score. It seem infinitely logical and indeed implied, that those with a higher wisdom (religious awareness) are better tapped into the spiritual cosmos. There is thus also a minimum wisdom of 6 to be a cleric.
I am going to allow clerics (Templar clerics), like magic-users above, to cast any spell up to the their maximum number of spells / level / day allowance. However unlike magic-users, clerics don't have spell books but rather than allow them the full range of all spells for that level immediately, I have chosen a staged increase. Their clerical spell knowledge increases over time at 1d4 spells / level, minimum determined by wisdom bonus AND the wisdom bonus additionally allows one to choose that many spells, the rest are randomly determined. Therefore it takes a few levels of advancement for a cleric to know all the spells for that spell level but a cleric with wisdom 13, is guaranteed cure light wounds, if they wish to choose it.
Wisdom ability score 4-5 allows a choice between negative in-game mechanics, no such choice is allowed at Wisdom 3.
Intuition Roll Rules - since role playing a wisdom higher than one's own is very difficult.