So I'm blatantly stealing a weapon invented by Alistair Reynolds and used in his novel The Prefect: the Whiphound.  It's an extensible/retractable whip that can snake along on the ground by its owner.  It's used to snare opponents, so it obviously should have Snare quality, just like Bolas do in the RT corebook (page 116).  

As opposed to the Bola,which is a Primitive weapon, the Whiphound should be guided by a Machine Spirit, and thus should not have the Inaccurate quality.  Should I give it the Accurate quality?  And what should I make the difficulty penality to Agility and Strength for slipping out of it and breaking free of it (respectively)?  

Any suggestions would be appreciated!

Not Accurate, but Flexible and Snare, sure.  Mono, too.  And give it a ST and AG rating of its own to make the escape rolls opposed tests.  If it fails, the target is still snared, if both succeed look to break the tie by the usual rules.  Alternatively, you could just hit the target with a -20 penalty to escape, but I think something the whip can roll is closer to the source.

If you want a more accurate one, buy quality.  I'd peg the base availability at Very Rare at least though.  Interrogation mode would also cost extra, and may flag as heretek depending on who you show it to.  

If you haven't read The Prefect, the best 40k example I can think of is this: remember when Eisenhorn is investigating a corpse and there's a splinter under his finger that turns into a metal snake?  That, but when at rest it's a handle.