Old English and Old Norse

Hey all,
A quick two questions that hopefully someone knows the answer to:

1) How does PGmc *Tiwaz -> OE Tig ?
"Tiges" is used in the OE Martyrology to refer to Mars, whereas in the
7th c Kentish Epinal (or Epinal-Erfurt) Gloss, the term for Mars
is "tiig".
Anyway, I assume *Tiwaz -> Tiw -- but then I cannot grasp the shift
from W-to-G. Any ideas?


2) Old Norse gives the words "tiggi" and "tyggi" to mean king or
leader, and the term "tiginn" to mean high rank or noble (based on both
Cleasby-Vigfusson's and Zoega's dictionaries).
Is there any way these could be related to OE Tig or is it simply an
issue of them being homophones?


As always, I am in your debt,
-Aydan