First off, I feel that all items with unique names should have unique properties, so I'd like the default ECB to grant Elf-like immunities to Sleep and Charm while equipped. Sure, this would be meaningless to an actual Elf, but the enchantments could have been added when the weapon was gifted to Yin Pon, or even to an earlier non-Elven bearer. In the same vein, the Ripper+2 has a unique name as well, so I think the weapon would benefit from altering its description to include how it imparts its enchantment to every arrow that it fires: The barbs on the arrowhead shrink while in flight, and re-enlarge again after the arrow lodges in the flesh of its victim, with the effect of making the wound more bloody and painful, especially when ripping the arrow free. Game-mechanics-wise, this would be represented by each hit from the Ripper doing an extra 1D2 Bleeding damage per round, for two rounds.

About being immune to Sleep: I've already noticed that some items that grant immunity to psionics are effective against plot-related events, like the party Unconsciousness that you get hit with upon entering the Eastern Tunnels, or more importantly the Sleep effect in the dream sequences. Should there be a new spell, "Cutscene Sleep," that these anti-psionic items (and the new Elven Court Bow) would not provide immunity to?

For ToB, one way to keep the Elven Court Bow in play is to make it the only source of Arrows+4. Once per day, the Bow can magically create 20 of them, and it would be sweet if there could be a race-specific casting as well, so that full-blooded Elves can use the spell twice, for 40 arrows, and all other races can use the spell once.

About British spellings: I'm surprised I never realized before how useful--and subtle--this could be. Having characters from long-standing Elven settlements, such as Suldenessellar and Evereska, use the British spellings while everyone else uses American, could be quite a powerful distinctive 'accent', without even taking the trouble of making sound files. But then again, if we're to keep to canon, British and Scottish accents are supposed to be unique to Waterdeep and its environs, with the accents denoting the upper and lower classes, respectively. Hmmm. This shall require mulling over. Dangit!