I've seen this motto spelled in two ways:

"So dorn donna dubfuilteh"

and

"So dorn dona dubhfuillebh"

as well as translated in two ways:

"This hand is raised against tyrants,"

and

"Here is the first for the dark blooded."

Any expert opinions on which is/are correct? You can view the motto in context here:

www.mcmahonsoforiel.org

Many thanks to all,
Seathrún

Seo dorn dona dubhfuilteacha...

Seo dorn dona dhubhfuiltigh?

Whoever said "This hand is raised against tyrants" had vivid imagination (or poor Irish). "Here's a fist to/for the dark-blooded" is the correct translation into Irish.

In old spelling
So dorn donna dubhfuillid
(but if you use our modern roman alphabeth you can't spell it like that, since it doesn't have lenition built into it)

Seo dorn dona dhuibhfhuillidh

I've no idea what the original meaning of the 'motto' was. but I would not totally dismiss the reference to 'Tyrants'.

What is the intended meaning of black/dark blooded? And why is a fist awaiting them?

Maybe the reference is to those with whom there is 'bad blood' -an old enemy or previous tyrant.

The stand alone 'dark bloooded' doesn't have any real meaning unless the interpretation is widened.

Just thinking out loud.