There’s a two-handed thunder hammer in the
BA Death Company box that would look good as a Bo.
Nunchucks as power mauls would be a good choice. If you can find modeled handles, cutting one off and attaching with modelling chain would be perfect.
For Raph, there’s a thread started about terminator sized sais.
If Grey Knights are an option, then maybe make the Sais counts-as falchions instead of Leo, and then have Leo treated as “power sword”.
Lastly, this seems ideal for Kill Team, as
GK are limited to 5 dudes based on the points. For a 5th member, I’d suggest Metalhead as the 5th turtle, maybe armed with
PF if that’s an option, or maybe a big gun.
I don’t have the book on me, but like I said, that would be a fun counts-as
KT army. Bonus points for using “Shurikan Catapults” for the ranged weapon bits.