These are bodkin, or armor-piercing, arrows.
In the arrow- and spear-head
thread pinned to the top of this sub-board you can see several
Roman finds that are similar.
However, the
Roman ones appear a
bit different. The main thing is that
Roman ones all have a clearly square (or diamond) cross-section.
I believe that ones like yours with a flattened diamond cross-section are
medieval though I haven't found the reference to prove it.
SC