AI identification & appraisal estimate

Mantis MT-8-S 'Vuja De' Balisong (Butterfly Knife)

Submitted photo of Mantis MT-8-S 'Vuja De' Balisong (Butterfly Knife)
Photo submitted by the user — not generated by AI

User's notes

Mantis butterfly knife

These notes were written by the person who submitted this item. Appraiser.AI has not verified them, and the AI's identification and estimate may rely on them.

AI Estimated Value

Not an official valuation

$65-$95

AI estimate as of January 9, 2026 · verify with a professional before acting

AI-Generated · Verify before acting

Everything on this page is generated by AI for informational purposes only. AI can make mistakes — the AI may misidentify items or misattribute them (artist, maker, brand, designer, origin, era). This is not an official valuation and should not be used for insurance, sale, tax, estate, legal, or lending purposes — or any decision requiring a certified appraisal. It is not an authoritative claim about any person, brand, or rights holder — do not share or rely on it as a factual statement about a third party. Always consult qualified professionals before making financial decisions.

This analysis also relies on unverified notes provided by the user, which may be incomplete or inaccurate and could affect the result.

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AI Item Analysis

This is a Mantis MT-8-S Vuja De butterfly knife, a distinctive tactical folder known for its unconventional design. The item features a 440C stainless steel blade with a modified American Tanto profile, characterized by its sharp angular tip and straight edge. The blade showcases a 'Stonewashed' finish, which provides a matte, textured surface designed to hide scratches. The handles are constructed from skeletonized stainless steel, finished in a matching bead-blast or stonewash grey. Notably, the skeletonization consists of rectangular cutouts that serve both to reduce weight and provide a more secure grip. The knife utilizes a sandwich-style construction with Torx screw fasteners, indicating a modern manufacturing era (likely 2010s). The tang of the blade is stamped with '440C', denoting the steel type. The condition appears used but well-maintained, with minor surface scuffs on the handle scales and some light pocket wear on the deep-carry pocket clip. The T-latch mechanism at the base of the handle is functional and intact. The design is unique for a balisong as the handle geometry is slightly curved, a signature element of the Mantis 'Vuja De' series, designed to improve ergonomics during both flipping and cutting tasks.

AI Appraisal Report

Upon inspection of the Mantis MT-8-S 'Vuja De' Balisong, I have identified the piece as a standard production model from the mid-2010s. The 440C stainless steel blade and skeletonized steel handles show authentic manufacturing hallmarks, including the correct laser-etched branding and industrial stonewashed finish. The condition is 'Used - Good,' exhibiting expected pocket wear and minor abrasions on the handle scales, which slightly devalues it compared to Mint-in-Box examples. The Vuja De is a niche collectible known for its unorthodox curved handle geometry. While Mantis Knives maintains a loyal following for their 'out-of-the-box' designs, the use of 440C steel—a mid-tier material—limits its ceiling compared to high-end balisongs using S35VN or M390. Currently, the market for discontinued Mantis folders is stable but modest; most secondary sales occur within enthusiast forums rather than high-end auction houses. The functional T-latch and intact Torx hardware suggest the knife has not been subjected to extreme 'fanning' or 'flipping' damage, which often plagues this category. Note that this appraisal is based on photographic evidence. A physical examination is required to verify the pivot smoothness and to ensure no hairline fractures exist in the handle slabs. Full authentication would be bolstered by the original 'Mantis' box and paperwork. Without physical handling, I cannot definitively confirm the absence of aftermarket sharpening or internal pivot modifications.

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