You have I 5, and I 6 is only a cheep upgrade away... - you should be hitting first anyways and so the benifit of the bonesword is negligable....
The lash whip is alright, but your best way to reduce the enemy attacks is to kill the models. Thus an extra attack would serve you better here, hence the extra scything talon.
Now, you can not fleet, and you are moving 12 each turn anyways, you may desire to shoot. so take a warp blast. Or you may find that your opponent enjoy filling your tyrant with more lead than a number 2 pencil - so a warp field would be handy here. Going up against psycher heaver armies? take shadow in the warp -it'll screw with them in a rather fun way. Or, are you playing an army that can match your speed, and you don't want to be charged? You already have the horror - now reduce their changes of passing it to charge you - psychic scream.
I typically can find a power to use, the most common being warp field and warp blast.
I like to run my tyrant as such:
BioMorphs: acid maw, A glands (I), Toxin Sacs, Winged, Toxic Miasma, x2 Scything Talons, Warp Blast - 194 pts
Alternatively if I have a bunch of point to kill (2000 + pts):
BioMorphs: Acid Maw, A glands (I), A glands (WS), Flesh Hooks, Implant Attack, Toxin Sacs, Toxic Miasma, Winged, x2 Scything Talons, Warp Field - 229 pts
or conversley, if running her in a small game (500 - 750 pts):
BioMorphs: Toxin Sacs, Winged, x2 Scything Talons - 143 pts
This gives me 6 attacks on the charge and I find that she is beautiful at destroying enemy armor (but dont hold to much stock in that - I am amazing at killing tanks - the dice gods love me, what can I say
)
as for the Fleshborers, rember they are str +1, which means that your lowly guants can get a str 5 gun, re rolling if failing to wound...
EDIT: Arg! coredumo beat me to it...