They bought guns, as many as they could afford and import. At the Battle of Adowa (or Adwa) in 1896, in their famous victory over Italy which preserved their independence until the 1930s, the Ethiopians had more guns that the Italians. This was not a victory of sword, spear and bow over modern arms, but a victory of more rifles over fewer rifles.

Traditional art of the battle is quite realistic in showing both sides well-armed:

• https://en.wikipedia.org/wiki/File:ItaloAbyssinianWarpainting.JPG

While some of the Ethiopian force didn't have guns, the majority did. For the story of how they got their guns and who from, see:

• https://www.reddit.com/r/AskHistorians/comments/970jd7/the_ethopian_army_during_the_first_italoethiopian/

Thanks for info

I've written on this before a bit, so would point to this older answer.