The Ectoplasmatist archetype for the Spiritualist gets an ability called Ectoplasmic Lash, which reads as follows:
Ectoplasmic Lash (Su)
At 1st level, as a full-round action an ectoplasmatist can manifest one or two lashes of ectoplasm tethered to her by wispy, ectoplasmic tendrils. If she manifests two lashes, she can wield them both as light melee weapons, each dealing 1d6 points of slashing damage (1d4 if the ectoplasmatist is Small) with a critical threat range and multiplier of 19–20/×2. If the ectoplasmatist manifests only one lash, she can manifest it either as a single one-handed melee weapon that deals 1d8 points of slashing damage (1d6 if the ectoplasmatist is Small) with a critical threat range and multiplier of 19–20/×2, or as a two-handed melee weapon that deals 2d6 points of bludgeoning damage (1d10 if the ectoplasmatist is Small) with a critical multiplier of ×2. Only the ectoplasmatist can wield or use these lashes. Dismissing any or all manifested lashes is a free action.
At 2nd level, the ectoplasmatist’s lashes gain a +1 enhancement bonus on attack and damage rolls, and are treated as magic weapons.
[... various other add-ons at progressive levels ...]
This ability replaces etheric tether, phantom, shared consciousness, fused consciousness, spiritual bond, and empowered consciousness.
They gain the ability to manifest these weapons, but it never actually states anywhere that they gain proficiency with them. Is there some blanket ruling somewhere to say that you're always proficient with class-given abilities?
Similarly, the Warlock archetype for the Vigilante has the Mystic Bolts class feature, which also never explicitly grants proficiency, but it does talk about taking Weapon Focus, which would imply that they are proficient.
It really seems like the assumption is that they are proficient, but I'm trying to find a ruling on it.