I searched and couldn't find this anywhere so I apologize if it's buried somewhere.
Can I use Word of Seizing on an Aura, and what can I then do with that Aura?
Scenario was: opponent used Word of Seizing on my Spectra Ward then attached it to his creature to block mine.
You can cast Word of Seizing on an aura, but a lot of the time it won't do much. You can't move it to something else. You just control it, but it will still be attached to the same permanent. In your example, Word of Seizing on a Spectra Ward doesn't do anything. However, if it was a Spirit Link your opponent would gain the life (if the creature dealt damage) since they control the aura.
I searched and couldn't find this anywhere so I apologize if it's buried somewhere.
Can I use Word of Seizing on an Aura, and what can I then do with that Aura?
Scenario was: opponent used Word of Seizing on my Spectra Ward then attached it to his creature to block mine.
Gaining control of an aura won't do anything unless the aura itself has an activated ability (something link crab umbra), which would allow you to use the activated ability. It doesn't allow you to reattach it to another creature. Think of it like pacifism. You control the aura, but you are attaching it to your opponents creature.
Can I use Word of Seizing on an Aura, and what can I then do with that Aura?
Scenario was: opponent used Word of Seizing on my Spectra Ward then attached it to his creature to block mine.
Gaining control of an aura won't do anything unless the aura itself has an activated ability (something link crab umbra), which would allow you to use the activated ability. It doesn't allow you to reattach it to another creature. Think of it like pacifism. You control the aura, but you are attaching it to your opponents creature.