You have to be a psyker to do it because, of course you're not fast enough to parry bullets. Like a Jedi, you put your sword in the bullet's path before it is fired. Eisenhorn isn't the only one to have done it. Eldar Banshees have as well (remember every one of those bastards is a psyker, just most of them don't have powers that are that useful for combat).

And on a side note, Katana's are nice swords, but they're frail because of the poor quality of (pre modern) Japanese steel. That's why they have to fold the blade with alternating hard and soft layers so many times to get a good (but delicate) blade while some luckier bastards can just use forge some wootz ingots (really, really good Indian steel) together and get an awesome sword.

http://www.youtube.com/watch?v=5Hy_A9vjp_s&feature=related

It's in German, but you'll get the gist. The second half is the good stuff. Do not watch if you can't bear to see a nice weapon get ruined.

Big deal.

Darth Vader parries Laspistol blasts with his HAND....

Ah! those poor swords!

It might not have ruined the western longsword so spectacularly as it did the Katana, but I'd wager that blade is riddled with micro-fractures, and now little more than a liability to anyone who wields it. In a clash like that it is very much dependant on the quality of the blade as to which comes of better. I had a sword break in half in a very similar incident (while attacking).

I am not entirely new to 40K, but I'm getting deeper into RTand picked up the Eisenhorn omnibus today as well as ordered my copy of RT. Begun reading the Inquisiton War books that I found in a used bookstore. Speaking of sentient swords, just look at the Eternal Champion series by Michael Moorcock, in particular Elric of Melnibone. His sword Stormbringer , hummed and moaned and was basically a demon/chaos/god transformed into a sword. Stormbringer could act on its own, but Elric fed off its energies to sustain his albino and ravaged body.