Actually, no. My paladin has recently acquired a holy sword that allows him to channel (per the Channeling rules in the BoED,) the power of a trumpet archon (adjusted to 10th-level via a 20 level monster class patterned after the astra deva monster class provided in MoTW.) He's 12th-level and this is his cohort, so as he increases in level, so too will his access to the trumpet archon's powers (the trumpet archon powers will "gain" a level each time he does). Channeling allows the Channeler to acquire all the (Sp) and (Su) abilities of the channeled celestial, but none of the (Ex) abilities. Everything else seemed crystal clear, except for the DR, which I couldn't find a designation for. If it were (Ex) then my paladin wouldn't acquire it while channeling. Since it's (Su), he does.
My paladin will be happy to hear that he can benefit from the archon's DR/evil while wielding his sword. Though sadly it won't help him against a large portion of the campaign's foes, which are devils (and therefore I believe all have Evil natural attacks and treat any wielded weapon as Evil as well.) Still, very useful for the mooks, summoned critters, etc. etc.
I ain't complaining.