pwys

Or perhaps “arlwydd pwys” means “the legitimate lord,” in opposition to usurpers, just as a wedded wife is styled “gwraig bwys,” as distinguished from a concubine.

Y Gododin A Poem of the Battle of Cattraeth Aneurin 1836

Rhuawn Bevr, ab Gwyddnaw Garanhir; sev yu gelwid felly achaws rhoddi eu pwys yn aur am danynt o ddwylaw au lladdes.”

Y Gododin A Poem of the Battle of Cattraeth Aneurin 1836