Hmm, this should probably be consulted with by an Icelandic.
It so happens that one of my colleagues are from the said country and in combination of my own interest in old Norse language, I may be of assistance.
Gladr should be pronounced "straight forward" like "Glağr"
G as in
gut
L as in
live
A as in H
ard
Ğ as in
them (although very soft)
R as in
rollerblade (but a rolling "r" like the Norwegian og Spanish pronounciation)
Edit:
Glağr means "happy" (more or less)
Edit 2:
Scratch that.
Glağr means "happyness" and Glağ means "happy".