I agree. And while we're at it, we can probably assume we all also support the existing New Entry already in the pipeline for 'shew [obs.] = zeigen':related discussion
Getting 'spake' in could be a little trickier since it's a past tense form; however, a single entry like 'spake [obs.] = sprach' could be helpful to German readers.
While thinking along these lines, it might be a good idea to check any other archaic verbs at the same time and be sure they're marked consistently.
So far LEO has, for example, 'hath [poet.] = hat'; if you call that poetic rather than obsolete, 'chuse' and 'shew' might be in the same category, since some modern writers use them for literary effect (as when writing historical novels using faux-18th-century language). However, I might still recommend [obs.] instead, since otherwise German users could get the mistaken idea that such words still occur in elevated diction.
It's undoubtedly impractical to add a whole slew of 2nd- and 3rd-person verbs in -st and -th, but it might be worth considering at least a few more archaic forms of 'to be,' 'to have,' and 'to do,' e.g.,