Grayflame and use magic device

[JorgR]

Use magic device always makes me scratch my head. But am I reading it correctly if I assume the following?

Bob the rogue has +20 use magic device and a +1 short sword with grayflame on it.

Grayflame:

This weapon responds to channeled positive or negative energy. When the wielder spends a swift action to channel energy through the weapon, it ignites with a strange gray flame that sheds light as a torch, increases the weapon's enhancement bonus by +1, and deals +1d6 damage (as the divine power from flame strike) to creatures struck by the weapon. This flame lasts for 1 round for every d6 damage or healing the channeling normally provides. When charged with positive energy, the flame is a silvery gray, good creatures are immune to the weapon's extra damage, and the weapon counts as a good and silver weapon for the purpose of bypassing damage reduction. When charged with negative energy, the flame is an ashen gray, evil creatures are immune to the weapon's extra damage, and the weapon counts as an evil and cold iron weapon for the purpose of bypassing damage reduction.

So he sees a nasty looking enemy, and uses UMD to try to emulate a class ability (channel energy) to activate his weapons grayflame-ability. He rolls 10 on his D20, making his effective level when using the ability 10 (20 ranks + 10 roll = 30. Effective level = check -20.) At level 10 a cleric has 5d6 of channel, making the weapon light up for 5 rounds.

[Umbral Reaver]

The rogue can pretend to have channel energy. He succeeds! The weapon thinks 'hey, this guy has channel energy; channel some energy, please!'. The rogue thinks on this, and realises he has done something pointless. He can pretend to have channel energy, but can't actually spend the swift action to channel energy into the weapon.

[MurphysParadox]

Yeah, you actually have to channel energy through the weapon, not just pretend to have the ability to channel energy. UMD can help with pretending, but it won't be able to actually perform the channel.

[darkwarriorkarg]

I'd let it slide, myself. Rogues don<t get much anyway.

Far more fun is the rogue pulling out thr holy avenger...

[JorgR]

Thanks for the input. I'll talk it over with my GM.

Is there any way to use the 'emulate class ability'-part of UMD for anything useful? And even though fun, the chances of a Holy Avenger showing up in a campaign are pretty slim.

Should perhaps be renamed "Use wand and scrolls"?