When a sword possesses unusual characteristics, it has a personality which is rated by combining its Intelligence and ego scores.
The sword will, of course, be absolutely true to its alignment, and, if the character who possesses the sword is not, personality conflict will result, i.e. sword versus character.
Similarly, any sword with an ego of 19 or higher will always consider itself superior to any character, and a personality conflict will result if the possessor does not always agree with the sword’s dictums.
The personality strength of a character is:
INTELLIGENCE + CHARISMA + LEVEL OF EXPERIENCE
Note level is reduced by 1 for every group of hit points of damage taken equal to the character’s average number of points per hit die for total levels of experience (rangers, for example, getting 2 dice at 1st level).
Example. A fighter of 7th level has 53 hit points: 53 + 7 = 7.6 - [this means] for every 8 points of damage he or she takes, his or her personality strength will be lowered by 1.
Whenever personality conflict occurs, the sword will resist the character’s desires and demand concessions such as:
removal of associates, henchmen, hirelings, or creatures of alignment or personality distasteful to the sword
the character divesting himself or herself of all other magic weapons
obedience from the character so that the sword can lead the expedition for its purposes
immediate seeking out and slaying of creatures hateful to the sword
encrustation of gems on pommel, hilt, scabbard, baldric, or belt and a special container for its safekeeping likewise of precious substances
magical protections and devices to protect it from molestation when not in use
that the character pay it handsomely for a11 abilities and powers the sword is called upon ta exercise in behalf of its possessor
that the character always take it along on all occasions
that the character relinquish the sword in favor of a more suitable person due to alignment differences and/or conduct
At any time that the personality score of a sword exceeds the personality score of the character who possesses it, the sword will dominate its possessor, and it can force any or all of the above demands or actually cause any of the following actions:
force its possessor into combat
refuse to strike opponents
strike at its wielder or his or her associates
force its possessor to surrender to an opponent
cause itself to drop from the character’s grasp
Naturally, such actions are unlikely where the character-sword alignment and purposes are harmonious. However, the sword might well wish to have a lesser character possess it so as to easily command him or her, or, a higher level possessor so as to better accomplish its goals.
All magic swords with personalities will desire to play an important role in the success of activities, particularly combat. Likewise, they are rivals, even if of the exact same alignment, and they will be aware of the presence of any similar weapon within 60 ft., and try the best to lead a possessor into missing or destroying the rival, unless this is totally inimical to its nature, i.e. a Holy Avenger would certainly not allow destruction of any other lawful good sword and might encourage discovery of same - even at the risk of having to face grim odds to do so...
Swords of this nature will never be totally controlled or silenced by the characters who possess them, even though they may be heavily outweighed by personality force. They may be powerless to force their demands, but they will be in there plugging. Even a humble +1 sword of unusual nature can be a vocal martyr, denigrating its own abilities and asking that the character only give it the chance to shatter itself against some hated enemy, etc.
N.B. Most players will be unwilling to play swords with personalities as the personalities dictate. It is incumbent upon the DM to ensure that the role of the sword is played to the hilt, with the DM assuming the persona of the sword if necessary.