How could the manticore belt's things not be weapons. Check out "weaponlike spells" from complete arcane, right before the feats section. Now check Soulmeld-Magic Transparency. Boom.
Weaponlike Spells are divided into "ranged" and "touch," and the "ranged" category includes things that require a ranged attack roll and/or a ranged touch attack roll. Examples of the former, being what we want, include Splinterbolt and Fire Shuriken. Now note that you can apply some of your combat related feats to your weaponlike spell. Technically this only qualifies for the ones listed in the book, but if this isn't proven by RAW, it sure as hell is one of the most logical houserules in the universe. Also note that you can apply spell boosts to your weaponlike spells (such as using Hunter's Eye to get sneak attack and deliver that sneak attack on a Scorching Ray, or by casting,
Prayer, which applies to spell damage from weaponlike spells), and with the Soulmeld-Magic Transparency, this should work out just fine. The Soulmeld-Magic transparency states that
"Soulmelds interact with spells and spells interact with soulmelds in the same way that a spell or a normal spell-like ability interacts with another normal spell or spell-like ability (with a limited number of exceptions as noted below).
If Soulmelds interact with Spells, and Spells interact with Soulmelds in the same way that Spells interact with Spell-Like Abilities and in the same way that Spell-Like Abilities interact with spells, then Soulmelds interact with Spell-Like Abilities the same way that Spell-Like Abilities interact with Spells etc etc.
But also:
If spells interact with spells in a certain way, soulmelds interact with spells in that same way, and therefore can interact with each other in the way that spells interact with each other.
This means that a soulmeld can enhance another weaponlike soulmeld the same way that a spell could enhance another weaponlike spell. Hence, in the most convoluted way possible, I've (hopefully) proven that Sighting Gloves work with weaponlike soulmelds, which the Manticore Belt is.