+0? You would be hard pressed to do that. Compare it to an elf...
ELVEN RACIAL TRAITS
-- +2 Dexterity, –2 Constitution: Elves are graceful but frail. An elf’s
grace makes her naturally better at stealth and archery.
-- Medium-size: As Medium-size creatures, elves have no special
bonuses or penalties due to their size.
-- Elven base speed is 30 feet.
-- Immunity to magic sleep spells and effects, and a +2 racial saving
throw bonus against Enchantment spells or effects.
-- Low-light Vision: Elves can see twice as far as a human in
starlight, moonlight, torchlight, and similar conditions of poor
illumination. They retain the ability to distinguish color and
detail under these conditions.
-- Proficient with either longsword or rapier; proficient with
shortbow, longbow, composite longbow, and composite
shortbow. Elves esteem the arts of swordplay and archery, so all
elves are familiar with these weapons.
-- +2 racial bonus on Listen, Search, and Spot checks. An elf who
merely passes within 5 feet of a secret or concealed door is
entitled to a Search check to notice it as if she were actively
looking for the door. An elf’s senses are so keen that she
practically has a sixth sense about hidden portals.
-- Automatic Languages: Common and Elven. Bonus Languages:
Draconic, Gnoll, Gnome, Goblin, Orc, and Sylvan. Elves
commonly know the languages of their enemies and of their
friends, as well as Draconic, the language commonly found in
ancient tomes of secret knowledge.
-- Favored Class: Wizard. A multiclass elf’s wizard class does not
count when determining whether she suffers an XP penalty for
multiclassing (see Experience for Multiclass Characters, page 56).
Wizardry comes naturally to elves (they sometimes claim to have
invented it), and fighter/wizards are especially common among
them.
Personally, I would be more inclined to drop the -2 Wis and replace it with -2 Con, but it's not absolutely necessary. The huge difference between your race and elves is the +4 save vs spells. Dwarves get away with +2 because of their reduced speed (which makes up for other good abilities as well). But +4 is pretty powerful. The +2 of your race is basically just like an elf's, but remember, if it's a spell, your race will get the +4 instead. The +2 would only apply to other effects.
The UMD is cool, but not worth bumping the ECL. The slashing damage is also cool, but I admit that I made a mistake. I assumed it was considered an armed attack. Since it is not, I'll immediately drop my recommending of a minimum modifier to +2, and again, it would be a low +2.
Like I said though, this is barely a +2 ECL. At 10th to 12th level, you could easily reduce the modifier to +1 ECL. That would let a player "catch up" a bit and would better represent their actual power level in comparison to +0 races.
Lastly, I think if you go with -2 Con instead of -2 Wisdom, reduce the +4 save vs spells to +2, and keep everything else, I'd go with +1. I don't think you could go much lower than that. But if you follow my suggestions, a good way to round it off a little more would be to supplement their low-light vision.
I know this sounds a little wacky, but I've seen this in game and its quite cool...add on darkvision 120 feet. Keep the low-light vision too though. What ends up happening is this. While standing in the area of a torch (light radius 20 feet), their low-light vision would allow them to see normally up to 40 feet away, then beyond that, their darkvision would kick in and allow them to see up to 120 feet away. So, they would see 40 feet in low-light and an additional 80 feet in darkvision. It may sound wierd at first, but in practice, it really does represent truly superior vision.
Also, regardless of whether or not you do the low-light+darkvision thing, I'd go ahead and grant a +2 bonus to Spot and Listen checks. Doing that would round it off even more, and if you do all of it, you'll have a strong and hardy +1 race, one that is definately worth taking, especially when compared to the genasi.
