Spines? That is far away from the necessary single target dps. The green bar of a WP brute will hardly ever move against spines.
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
I have done a few duels against EM/WP brutes as an Inv/SS tank. Not surprisingly I have no hope of taking them out while their toggles are up, both because they resist smashing damage fairly well and because they regenerate too fast. I suspect the best avenue for a melee character would be to mez them. EM for tanks has the option of stacking stuns, as well as pouring on the burst damage once the Brute shields drop. Slotting for stun duration or using the Vanguard accolade, together with Hasten or Geas to boost the recharge might be able to succeed. Timing it to happen after Strength of Will has just dropped would be best.
I am a bit in the dark about what other melee characters has the ability to stack toggle-dropping mezzes however. Except for Energy Mastery, the tank ancillary power pools contains a few holds that could help.
A hold from a ancillary pool is mag 3. Ss and stone have holds mag 3 and 4. To stack 3 or 4 holds is very easy, in these conditions (ancillary hold + ss or stone hold, two times). For instance, it detoggles easily the rooted of my stone brute - without granite...
Fortunately for brutes, the most of tanks prefer the energy mastery ancillary pool ^^
And I'm curious to see fire/ scrappers in pvp, against /elec and /wp brutes.
To stack 3 or 4 holds is very easy? Please consider the lowered base durations for mezzes in PvP. That means that even very IO-heavy tanker builds with Hasten running can only stack one hold from KO Blow / Seismic Smash and two from ancillary holds at best, adding up to Mag 9 or 10 respectively... which is not enough to overcome Indomitable Will. And the possibility of the brute having slotted Aegis Status resistance doesn't make things exactly easier... plus the fact that the brute probably won't need Strength of Will against a tanker other than for the recovery boost, so waiting for such an opening could take some time. 
The only way to circumvent this would be to slot KO Blow / Seismic Smash as hold rather than damage attack, but I think that would be too much of a sacrifice and greatly hurt your damage output.
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
I've been looking a bit at slotting up the KO-blow for Hold duration; it does seem to be possible to do so without sacrificing too much in other areas (damage, recharge, end reduction) although you will have to resort to mixing the Melee damage and Hold purple set to reach that point. Damage enhancement will be a bit lower than with a set of Crushing Impact, but still in the ED range. Recharge and Hold will comfortably reach levels where ED kicks in.
Of course, this will not help much unless the Tanker has some other Hold power available. It will still be too difficult to stack sufficient magnitude to overcome a Brute level mez protection.
It might come in handy to prolong the Hold if the Tanker can manage to drop the mez protection toggle with Brawl though, unlikely as that is. Without extra Hold powers, I would still expect the Willpower Brute to win.
[/color]<blockquote><font class="small">En réponse à:[/color]<hr />
The only way to circumvent this would be to slot KO Blow / Seismic Smash as hold rather than damage attack, but I think that would be too much of a sacrifice and greatly hurt your damage output.
[/ QUOTE ]
Toggles dropped = between +20% dmg and +70% dmg (depending on the armor set and the type of damages). I don't see that as a sacrifice ^^
By mixing sets, you can have +60% dmg and +40% hold on your hold (KO Blow, for instance). With haste and +30% rech from bonuses (reachable without purples), you can stack 4 holds easily.
spines/fire could be a real dangerous build.