Here's a modest update:
I've gone about as far as I can do with this until my supply of green stuff arrives.
I started with this figure:
This is basically a standard Praetorian Lieutenant model, but I had already reshaped the sword, making it a powersword rather than a chainsword. I needed to strip the paint from the model and do some more work:
I removed the sword's handguard and reshaped the blade into a short sword. I am considering reshaping the blade further in order to give it the distinctive Anglo-Saxon tapered look. I then ground the helmet and face down to give me a nice base to work on.
And that, pending kneadatite, is all folks.
Apart from the name. The British Museum site plays it coy about the identity of the helm's owner, but the Sutton Hoo site declares him to be Rædwald, King of East Anglia and later, one of the most powerful figures in Anglo-Saxon history.
Accordingly, this character shall be called Major Rædwald, 22nd regiment, Praetorian Guard.