Angels; you don't hear much about them these days.

[AngusMcDoon]

The whole point of an angel is to change the angle of the chain pull so it's pulling the anchor horizontally rather than up. A smallish weight pulling at 90 degrees on a long chain will have a huge impact. That's why you can sweat mooring lines on 300 ton boats. Incidentally (some connection) allspars have started selling these http://www.technicalmarinesupplies.co.uk/brands/anchor-buddy/
No idea whether they are any good.

It will change the angle by a few degrees, same as happens when you sweat the line on your 300 ton boat. If the rode is bar tight because it's blowing a hoolie there is not a walrus in Waitrose's chance that the rode at the anchor will suddenly become horizontal. The tiny change in rode angle at the anchor will have minimum effect on its holding. The weight of the angel would be much better invested in a bigger anchor.

Just done a back of an envelope calculation...

50m rode
10m from rode attachment point on boat above sea bed
10kg angel half way along rode
1000kgf wind force on the boat
Assuming warp rode so ignoring catenary
Angle of pull on anchor above horizontal without angel: 12 degrees
Angle of pull on anchor with angel: 11.4 degrees