"wouldnt that damage the radio to use a uhf antenna on a vhf radio?
ive seen people use 800mhz antennas on uhf radios before"
Contrary to Hollywood, you cannot tell what an antenna is just by looking at it.
An 800MHz antenna *is* a UHF antenna, there's nothing off about that.
But if you look at the parts catalogue from any major company (i.e. Motorola) you'll see that their UHF and VHF handheld antennas are often color-coded, because they come in "stubby" and "regular" lengths for both UHF and VHF and the two can be nearly identical.
Rubberized handheld antennas are usually helically wound antennas with a much longer wavelength than the physical length of the antenna. And just as with ham radio antennas, one rubber duck can be tuned to work as both a 2m. VHF antenna AND a 70cm. UHF antenna. It is 1/4 wave for one and 5/8 wave for the other, but that's not a real problem. It is "tuned" for acceptable performance on both UHF and VHF.
But yes, if you had a tuned UHF antenna that wasn't co-incidentally "tuned" for VHF, it could produce a high SWR and that could ruin the VHF radio. More likely, a modern radio would dial back power and just transmit very poorly, if at all, while still receiving. Not so much "ruined" but made useless. Older dumber radios would, yes, burn themselves out.