I got a Rageblood Barbarian.
I use his daily power Bloodhunt Rage and enter the rage of the bloodhunt which gives me a bonus to melee attack rolls equal to my con modifier as long as I or the target am bloodied.
Next turn I use my encounter power, Avalanche Strike, which is 3(W) + Str mod(4) +...
Says on page 120 of the dmg:
"If the trap constitutes an encounter or is part of an encounter...they do earn XP if they manage to disarm or destroy it."
Look at any power. After the writing "at will/ encounter/etc" it will often
be followed by "weapon" or "implement". If you are using a power that
does not say "weapon" I would say the player cannot utilize the weapon focus benefit since the staff is not being used as a weapon.