I like the idea of replacing pencil by pen in general, but this pen still needs work. Please try it in place (on the toolbox) and see how it fits with its neighbours (just replace the old icon in icons.svg). Problems I see:

- it's cut on the top, while the pencils are shown in whole

- the slant is a bit different, and the pen seems to be "broken" in the middle

- the pen is rotated flat towards us, I would prefer it in a bit more natural posture, more 3D

Please post a bitmap screenshot of the toolbar with the new icon, it's much easier to judge it that way.