This could be pretty cool... Maybe the victim must be touched by the gauntlet, gets a Save, but a Fail causes the target to completely disappear, leaving the Party confused about what they are doing, standing around with weapons in hand, with no apparent foe present. Might be a way for a particularly generous - or difficult! - DM to give the Party an 'out' when confronted by an overwhelming foe. Of course, if the foe never existed... it's not worth any XP, and never accumulated any treasure. Beats Total Party Kill, don't it? No memory of ever encountering the target remains.
"When did I use my Invisibility Potion?" "Why am I down to half HP?"
Would definitely require some limitation, possibly a very small number of charges, or use only once/year, or even a one-shot. Could possibly take different forms: a lidded box which contains a mystery which cannot be viewed, or has a big red button on top, or a crystal dagger which emits a prismatic cone, maybe a weapon which changes form every day...
