Prerequisites, Wis 15, Beastmastery Class Feature, Ranger
Benefit: Your Beast Companion adds your Wisdom Modifier to its attack and damage rolls.
In an effort to bring some more damage to the class, my DM approved this feat. Honestly, I think it should be a part of Beasts in general, but you take what you can get.
With this, a Beast will have good accuracy and damage, but still fall behind Multiattacks. It has done really well in my campaign thus far.
Great feat. Aside from the name and no prerequisite Paragon Tier, this is nearly identical to a house-ruled feat I created for my homebrew games after Martial Power was released. Excellent! 
I think that Wisdom to attack rolls is a little strong. Wisdom to damage I don't see any problem with.
Well, you gotta keep in mind that it has to make up for several things which PCs get that Beasts don't, such as a plethora of magic items, power bonuses, loads of feat support and class feature bonuses.
The Wisdom modifier bonus would be totally broken on the PC, but on a Beast Companion? I'd say it's breaking even.
There is nothing overpowered about using a Ranger's Wisdom modifier for both attack & damage {in relation to the Beast}, our group has been "playtesting" this kind of houserule since Martial Power was release, with no ill effects. Instead, such a feat does the opposite of what L_V suggests; it gives Beastmaster Rangers an extra level of oomph, which they trade in for when they take the Beastmaster style.
Remember; feats are a valuable commodity, trading in one feat for a bonus for your beast companion only is a sacrifice on your own personal power. I prefer to keep such a feat at Paragon Tier, but too each their own.
What about A flat boost?
+2 (Feat bonus) Hit and damage
+3 (Feat bonus) Hit and damage at level 15
+4 (Feat bonus) Hit and Damage at 25
at least keep it in like with other feats like it.
but thats just me i know a Beast master that has a +6 Wis mod (and hes not even epic) for beast synergy (more damage/attack) and that would actually make it so his pet would have a better to hit than him, by about 3 or 4 points and thats not whats suspose to happen IMO.
I would make it a static bonus like Rampant suggested
+2 (Feat bonus) Hit and damage
+3 (Feat bonus) Hit and damage at level 15
+4 (Feat bonus) Hit and Damage at 25
at least keep it in like with other feats like it.
Level 11 and 21 are probably better levels to have it upgrade, should it be offered as a feat at any level. I personally think it ought to be Level 11+ as a prerequisite, and provide +2 at 11th, and +3 at 21st.
but thats just me i know a Beast master that has a +6 Wis mod (and hes not even epic) for beast synergy (more damage/attack) and that would actually make it so his pet would have a better to hit than him, by about 3 or 4 points and thats not whats suspose to happen IMO.
This is EXACTLY why the static bonus should be used.
Having playtested both sides of the coin, I must say that neither option is better then the other, whether that be a bonus based on Wisdom or a static bonus.
The damage bonus is optimal for the Ranger, which is a Striker class and thus focuses on doing damage, a damage bonus many Rangers sacrifice when they take the Beast Companion style.
The attack bonus is minimal, since the majority of Ranger powers rely on the Ranger's ability to hit, not the Beast Itself. The attack bonus is more useful for when a Beast attacks on It's own, using It's own abilities, as stated above.
As far as houseruling, I say take your pick and use whichever suits your Group more. Both are great options, neither is better then the other.