Bonesword and lash whip or a pair of boneswords are the best setup in my opinion.
He needs a power weapon to make use of his 4 attacks and ws6. Rending claws and scything talons aren't good enough in this respect.
I prefer the bonesword/lash whip, as he can be targeted separately in combat, due to being an independant character. It ensures that he goes before those in base-to-base that can target him, and before any enemy independant character that faces him. Two boneswords are better for independant character killing, but will have you going at I5, so its a personal preference decision.
However, lash whips are the closest you will generally get to grenades in the Tyranid army, so I prefer to field them wherever I can.
I prefer a deathspitter as second weapon, as I usually field him in a warrior brood, which will have some form of gun to make use of the unit BS4 upgrade. The warriors themselves depend on points available/army list. I either use a cheap unit with deathspitters to act as objective holders/ranged support (the threat of the prime makes them harder to dislodge from objectives), or a combat unit with boneswords/lash whips and devourers to make use of BS4.
Either way I'd recommend Regenerate on the prime as being one of the few models where it's worth the points, as it can help with wound allocation when sticking the occasional wound on the T5 prime to save a warrior from a lascannon/krak missle shot.
Last edited by Scotty80; 11-02-11 at 03:48 PM.