I am trying to find a book I read in the late 90s.
It starts with this boy and his family moving into some relative's house. The boy finds a room of weird stuff, including a weird looking sword, a stuffed/mounted monster head, and a device that creates a portal to travel through time. The boy travels to a few different time periods, and at one point is in a battle between aliens and humans, and the aliens have disintegration guns. He is able to freeze time, and takes all the aliens' guns and lays them at the feet of the humans, and then unfreezes time.
Also, I believe the cover of the book had the boy falling/getting sucked into a swirl. Possibly mostly blue and white.
- long strange sword
- stuffed monster head
- cover was blue and white with vortex sucking in the boy
- time travel device was some type of vest, or hung around his neck with controls on his chest
- traveled to several time periods
- had a black and white drawing inside near the end depicting an alien shooting a human, which caused the human to basically melt
- the boy freezes time and steals all the aliens guns and gives them to the humans
UPDATE: Been thinking about this again, and I think the relative may have been the boy's future self. The sword and monster head are all gained by him throughout the book.